Rhubarb Oat Bars with Sugar Cinnamon Topping {Easy}

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Rhubarb oat bars: Discover this easy recipe with a delicious sugar cinnamon topping. Perfect for a sweet treat or snack that everyone will love!

rhubarb oat bars with sugar cinnamon topping easy

I was delighted when a friend gifted me a bunch of  fresh rhubarb in early spring. Making a mental note to make sure to plant some of my own rhubarb for next year so that I can make the most of rhubarb season. I got to the kitchen right after that. I make several different rhubarb recipes, but these Rhubarb Oat Bars are one of our favorite rhubarb desserts. You can whip up this great recipe in a few minutes, and the whole family will enjoy them. You can also adjust the amount of sugar in this recipe, and take it from a dessert recipe to a healthy snack.

rhubarb oat bars in a pan

Why You’ll Love This Recipe

  • This Rhubarb Oat Bars recipe made with sugar cinnamon topping is so simple to make. It uses only natural ingredients that you probably already have in your pantry.
  • The whole thing is very fast to make. Your kids can help and you will have a delicious afternoon treat ready in no time. 
  • Rhubarb has a number of nutritional benefits that this recipe allows you to harness 
  • Rhubarb is so versatile! If you want another, delicious way to prepare it, try this Rhubarb Crisp Recipe

Join me as I choose to see the beauty everywhere around me during those early summer days at the homestead. From baking delicious Rhubarb Crisp & Rhubarb Oat Bars to making a Wattle Fence.

What You’ll Need

Tart Rhubarb Filling

  • 4 cups (480g) chopped rhubarb stalks
  • 1/2 cup (110g)  brown sugar 
  • 1 tbs water
  • 1 tbs lemon juice

Oat Crust

  • 1 1/4 cups (150g) all purpose flour
  • 1 1/4 cups (115g) quick oats (or instant oats)
  • 2/3 cup (150g) brown sugar 
  • 1/2 cup (115g) unsalted butter
  • 1/4 tsp salt

Topping

  • 2 tbs brown sugar 
  • 2 tsp ground cinnamon

Tools

  • baking dish
rhubarb oat bars

Instructions

Prep

  1. Preheat oven to 350F (180C)
  2. Line the bottom of a baking dish with parchment paper 

Make Filling 

  1. In a saucepan add the chopped rhubarb, sugar, water and lemon juice.
  2. Simmer on low-medium heat for about 10 minutes. The rhubarb should soften, but still maintain it’s shape. 
  3. Turn off the heat, and let rhubarb mixture rest.

Make Oat Crust

  1. In a large bowl, mix the flour, oats, sugar and salt together
  2. Stir in the melted butter. Mix until combined.
  3. Set 1/2 cup of the oat mixture aside for later. 
  4. Add the remaining oat mixture to your prepared baking pan. Press the mixture firmly and evenly into the bottom the pan.

Mix the Topping

  1. In a small bowl, mix together the sugar and cinnamon

Assemble

  1. Spread the cooked rhubarb mixture evenly over the oat crust.
  2. Sprinkle the 1/2 cup of oat mixture you had set aside, over the top of the rhubarb. 
  3. Sprinkle the top with cinnamon and sugar mixture
  4. Bake for 1 hour, until the top is nice and golden and the rhubarb is bubbling.
  5. Allow the entire thing to cool for at least 2 hours before cutting into squares.
close up cinnamon sugar topping

FAQ

Yes, you can use frozen rhubarb. Make sure to thaw and drain it well to remove excess moisture before using it in your recipe.

Wash and trim the rhubarb stalks, then cut them into small, even pieces, typically around 1/2 inch. This ensures even cooking and a good texture in the bars.

Yes, you can add other fruits such as fresh strawberries to make strawberry rhubarb oatmeal bars.  Apples or other berries are also a good optiuon to complement the tartness of the rhubarb. Adjust the amount of sugar accordingly to achieve a perfect balance of flavors.

The bars are done when the oat topping is golden brown and the rhubarb filling is bubbling around the edges. You can also test with a toothpick; it should come out clean from the center of the bars.

Yes, you can reduce the amount of sugar, especially if you prefer a less sweet dessert. Keep in mind that reducing the sugar will make the bars less sweet and may affect the overall texture slightly.

Rhubarb oat bars are delicious on their own, but they can also be served with a scoop of vanilla ice cream, whipped cream, or a dollop of yogurt for added richness.

Use a 9×13-inch baking pan for this recipe to ensure even baking and proper thickness of the bars.

If your filling is too runny, it might be due to excess moisture in the rhubarb. Make sure to drain any excess liquid from thawed frozen rhubarb. You can also add a tablespoon of cornstarch or flour to the rhubarb mixture to help thicken it.

Tips

1. Choosing Rhubarb:

  • Freshness: Use fresh, firm rhubarb stalks for the best texture and flavor. If using frozen rhubarb, thaw and drain it thoroughly to remove excess moisture.

2. Preparing the Rhubarb:

  • Even Slices: Cut the rhubarb into evenly sized pieces, about 1/2 inch thick, to ensure uniform cooking and a consistent texture in the bars.

3. Enhancing Flavor:

  • Balancing Tartness: Rhubarb is naturally tart, so adjust the amount of sugar to your taste preference. Adding a splash of vanilla extract or lemon juice can enhance the flavor profile.
  • Complementary Fruits: Consider adding strawberries or apples for added sweetness and flavor.

4. Cooling and Cutting:

  • Cooling: Allow the bars to cool completely in the pan before cutting to ensure they hold their shape.
  • Cutting: Use a sharp knife to cut into squares or rectangles for neat, even pieces.

5. Dietary Adjustments:

  • Gluten-Free: Use gluten-free oats and flour to make the bars gluten-free.
  • Vegan: Substitute butter with a vegan alternative or coconut oil for vegan bars.

6. Serving Suggestions:

  • With Ice Cream: Serve warm with vanilla ice cream or whipped cream for an extra indulgent treat.
  • As a Snack: Enjoy as a snack or quick breakfast option.

Storage

Store the cooled bars in an airtight container at room temperature if planning to consume them within 1-2 days. Ensure the container is tightly sealed to maintain freshness.

For longer storage, place the bars in an airtight container and store them in the refrigerator. They can typically last up to 4-5 days when refrigerated.

  • To freeze the bars, first ensure they are completely cooled. Wrap individual bars or the entire batch tightly in plastic wrap to prevent freezer burn.
  • Place the wrapped bars in a freezer-safe container or zip-top bag, removing as much air as possible before sealing.
  • Frozen bars can be stored for up to 2-3 months.
  • Thaw frozen bars in the refrigerator overnight before serving. Alternatively, you can reheat them in the oven at a low temperature until warmed through.

1. Thawing:

  • Room Temperature: Remove the pretzels from the freezer and let them thaw at room temperature for about 1-2 hours.
  • Refrigerator: Alternatively, you can thaw them in the refrigerator overnight.

2. Reheating:

  • Oven Method: For the best texture, reheat the thawed pretzels in a preheated oven at 350°F (175°C) for about 10 minutes, or until they are warmed through and the exterior is crisp.
  • Microwave Method: If you’re in a hurry, you can microwave the pretzels. Wrap them in a damp paper towel and microwave on high for 20-30 seconds. This will warm them up but might make the exterior a bit softer rather than crispy.

3. Optional Step:

  • Buttering: For added flavor, brush the pretzels with melted butter after reheating. You can also sprinkle them with a little extra coarse salt if desired.
rhubarb oat bars in a pan

Rhubarb Oat Bars with Sugar Cinnamon Topping

Rhubarb oat bars: Discover this easy recipe with a delicious sugar cinnamon topping. Perfect for a sweet treat or snack that everyone will love!
Prep Time 30 minutes
Cook Time 1 minute
Total Time 1 minute
Serving Size 16

Ingredients

  • 4 cups 480g chopped rhubarb stalks
  • 1/2 cup 110g brown sugar
  • 1 tbs water
  • 1 tbs lemon juice
  • 1 1/4 cups 150g all purpose flour
  • 1 1/4 cups 115g quick oats (or instant oats)
  • 2/3 cup 150g brown sugar
  • 1/2 cup 115g unsalted butter
  • 1/4 tsp salt
  • 2 tbs brown sugar
  • 2 tsp ground cinnamon

Instructions

Prep

  • Preheat oven to 350F (180C)
  • Line the bottom of a baking dish with parchment paper 

Make Filling 

  • In a saucepan add the chopped rhubarb, sugar, water and lemon juice.
  • Simmer on low-medium heat for about 10 minutes. The rhubarb should soften, but still maintain it's shape. 
  • Turn off the heat, and let rhubarb mixture rest.

Make Oat Crust

  • In a large bowl, mix the flour, oats, sugar and salt together
  • Stir in the melted butter. Mix until combined.
  • Set 1/2 cup of the oat mixture aside for later. 
  • Add the remaining oat mixture to your prepared baking pan. Press the mixture firmly and evenly into the bottom the pan.

Mix the Topping

  • In a small bowl, mix together the sugar and cinnamon

Assemble

  • Spread the cooked rhubarb mixture evenly over the oat crust.
  • Sprinkle the 1/2 cup of oat mixture you had set aside, over the top of the rhubarb. 
  • Sprinkle the top with cinnamon and sugar mixture
  • Bake for 1 hour, until the top is nice and golden and the rhubarb is bubbling.
  • Allow the entire thing to cool for at least 2 hours before cutting into squares.

Notes

1. Choosing Rhubarb:

  • Freshness: Use fresh, firm stalks for best results. If using frozen rhubarb, thaw and drain thoroughly.

2. Preparing the Rhubarb:

  • Even Slices: Cut into ½-inch pieces for uniform cooking and texture.

3. Enhancing Flavor:

  • Balancing Tartness: Adjust sugar to taste; add vanilla extract or lemon juice for flavor.
  • Complementary Fruits: Add strawberries or apples for added sweetness.

4. Cooling and Cutting:

  • Cooling: Cool completely in the pan before cutting.
  • Cutting: Use a sharp knife for clean, even pieces.

5. Dietary Adjustments:

  • Gluten-Free: Use gluten-free oats and flour.
  • Vegan: Substitute butter with a vegan alternative or coconut oil.

6. Serving Suggestions:

  • With Ice Cream: Serve warm with vanilla ice cream or whipped cream.
  • As a Snack: Enjoy as a snack or quick breakfast.

Storage

1. Room Temperature:

  • Store cooled bars in an airtight container at room temperature for 1-2 days.

2. Refrigeration:

  • Store in an airtight container in the refrigerator for up to 4-5 days.

3. Freezing:

  • Preparation: Cool bars completely.
  • Wrapping: Wrap individually or as a batch in plastic wrap.
  • Storage: Place in a freezer-safe container or zip-top bag for up to 2-3 months.
  • Thawing: Thaw in the refrigerator overnight or reheat in the oven at a low temperature until warmed through.

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