Strawberry Rhubarb Oatmeal Bars
It’s rhubarb season – try these Strawberry Rhubarb Oatmeal Bars with a crunchy oatmeal cookie crust and a thick layer of fruit compote. Easier than a pie, but just as delicious!
Rhubarb! I really enjoy receiving rhubarb in CSA boxes, because it’s somewhat of a novelty vegetable for me. It’s not something I’ve ever actively looked to purchase, but I’m excited to use it when it falls into my lap.
It’s really a strange domesticated vegetable when you think about it. It’s too tart to really use unless it’s cooked down with lots of sugar. So… let’s turn this bitter, somewhat inedible stalky thing into a dessert!
Also, there’s the whole vegetable/fruit debate. While rhubarb actually a vegetable, a New York court deemed it a fruit for tax purposes in 1947.
Fruit? Dessert? Whatever. Let’s talk about how to use it!
As it so happens, our CSA box also included strawberries. Strawberries and rhubarb in the same week? Our CSA basically begged us to make a strawberry rhubarb dessert!
With a one-month-old at home who always wants to be held, I knew a pie was out – who has time to roll out a pie crust?! So instead, I opted for much quicker strawberry rhubarb oatmeal bars. These came together quickly and as an added bonus, are much easier to eat than a pie (one-handed while holding a baby!).
And you know what? They were easier to make, easier to eat, and every darn bit as delicious as a full-on pie. Pie bars to the rescue!
(Looking for other rhubarb ideas? Don’t miss this roundup post with all the Best Rhubarb Recipes!)
Ingredients and Substitutions
Let’s start by talking about some of the key ingredients you’ll need, along with some substitution options.
For the strawberry/rhubarb layer:
- Fresh Strawberries: I always like to use fresh strawberries when I can, but frozen strawberries can be substituted as well.
- Fresh Rhubarb: Similar to strawberries, frozen rhubarb can also be used instead of strawberries. You may need to cook down the mixture for longer if you’re using frozen fruit.
- Cornstarch: Cornstarch is the thickener we’re using for these bars. If you don’t have cornstarch, you can use flour, but use twice as much. Cornstarch has double the thickening power of flour.
For the Oatmeal Base:
- Flour: To keep these bars gluten-free, you can substitute a 1:1 gluten-free baking mix for the all-purpose four.
- Spices: Ginger, cinnamon, and nutmeg are my favorite spices to use but any spices that would work well in a blueberry pie (such as cardamom) would be delicious in these bars as well!
- Butter: Use unsalted butter at room temperature (cool, not cold, but not too warm!). A dairy-free butter can also be used.
- Brown Sugar: In addition to granulated sugar, I love to include brown sugar for both extra moisture and a slightly nuttier flavor. If you don’t have brown sugar, you can use replace it with all granulated sugar.
- Rolled Oats: Make sure to use old-fashioned rolled oats, not instant oats or quick oats!
These bars are delicious on their own, but I also love to top them with homemade blueberry sauce, which can be made with fresh or frozen blueberries.
Baking with Rhubarb
When it comes to selecting rhubarb, freshness is key. Look for stalks that are firm and crisp, with a bright and vibrant color. Avoid stalks that are limp, discolored, or have soft spots.
Remember, the color can vary from deep red to green, depending on the variety, so don’t be alarmed if you come across different shades. Rhubarb that is redder isn’t more flavorful or fresher than pale pink or green!
One of the challenges with baking with rhubarb is its high water content, which can lead to sogginess in baked goods. We’re going to combat that in two ways in these strawberry rhubarb oatmeal bars.
First, we’ll cook down the rhubarb and strawberries with cornstarch, which has great absorption and thickening power. Cornstarch can absorb up to 8 times its weight in liquid.
Secondly, we’re adding oats to our crust, which also helps absorb any excess liquid and ensures the bars won’t be soggy. That’s right – oatmeal crusts aren’t just delicious, they actually play a role in liquid absorption!
Don’t worry – there’s not a lot of liquid left and the crust stays crispy on the bottom, but it’s a little extra insurance protection. Why are oats better than flour? It’s time for my favorite subject… kitchen chemistry!
Old-fashioned rolled oats are a whole grain product, meaning the brain layer is still present. This bran layer is high in pentosans, a style of carbohydrate, which are even more absorbant than starch. Refined white flour has this brand layer removed, and thus is able to absorb significantly less liquid.
Recommended Tools to Make Strawberry Rhubarb Bars
- 3-Quart Saucepan: Use a metal, heavy-bottomed saucepan to cook the strawberry rhubarb mixture.
- 9 x 13-inch Baking Dish: A metal baking dish conducts heat well, but use a lighter-colored metal to help prevent the crust from getting too dark.
- Stand Mixer: A handheld electric mixer works too, but this stand mixer (mine is over 15 years old!) makes everything so easy.
- Beater Blade: Whenever I use a beater attachment for my mixer, I always reach for this Beater Blade, which wipes down the side of the bowl for you!
Tips and Tricks for the Best Strawberry Rhubarb Oatmeal Bars
- Make sure to use old-fashioned rolled oats, not quick-cooking oats or instant oats! Both the texture and structure of the bars require old-fashioned oats.
- Line your baking pan with aluminum foil or parchment paper, leaving some overhang on the sides. This makes it easier to lift the bars out of the pan once they’re baked, simplifying cutting and serving.
- When spreading the fruit compote over the crust, aim for an even layer spread over the crust. This ensures that every bite of your bars has a perfect blend and helps the bars cook evenly.
- Allow your bars to cool completely in the pan before slicing. This gives the filling time to set and the bars to firm up, making clean cuts without crumbling.
- Strawberry rhubarb oatmeal bars can be stored in an air-tight container at room temperature for up to 2 days. For longer storage, refrigerate for up to 5 days or freeze for up to 3 months. Place a piece of parchment paper or wax paper between layers of bars to prevent them from sticking to each other.
More Fruit Bars:
- Peach Pie Bars
- Raspberry Pie Bars
- Homemade Fig Bars
- Cherry Pie Bars
- Blackberry Pie Bars
- Berry Oatmeal Crumble Bars
- All Dessert Bars ≫
For the Strawberry/Rhubarb Layer
- 1 quart (650 grams) strawberries, sliced
- 2 cups (240 grams) rhubarb, sliced into half-inch pieces (about 6 stalks)
- 1/2 cup (99 grams) granulated sugar
- 1 tablespoon lemon juice
- 4 teaspoons (9 grams) cornstarch
- 1 1/2 teaspoons vanilla extract
For the Oatmeal Crust:
- 1 3/4 cup (210 grams) all-purpose flour
- 1/2 teaspoon baking powder
- 1/2 teaspoon salt
- 1/2 teaspoon ginger
- 1 teaspoon cinnamon
- 1/2 teaspoon nutmeg
- 1 cup (226 grams) unsalted butter, room temperature
- 1 cup (213 grams) brown sugar
- 1 cup (198 grams) granulated sugar
- 2 large eggs
- 2 teaspoons vanilla extract
- 3 cups (267 grams) old-fashioned rolled oats
For the Blueberry Sauce (optional):
- 1/4 cup (50 grams) granulated sugar
- 2 teaspoons cornstarch
- dash salt
- 1 pint (340 grams) blueberries
- 2 tablespoons lemon juice
- Make the strawberry/rhubarb compote. Combine all ingredients for the strawberry/rhubarb layer in a medium saucepan and toss with a wooden spoon to coat the fruit in the sugar and cornstarch. Cook over medium heat until rhubarb is fork-tender and juices have thickened, about 6-8 minutes. Set aside to cool.
- Preheat the oven to 350°F. Cover a 9×13-inch baking pan with parchment paper or aluminum foil, leaving an overhang on both ends of the pan. Spray the foil with nonstick cooking spray.
- Make the oatmeal crust. In the bowl of a stand mixer, beat the butter on medium speed until fluffy, about 2 minutes. Add the sugars and beat until well combined, another 2-3 minutes. Reduce the mixer speed to low and add in eggs, one at a time. Add vanilla and mix until combined.
- Add flour, baking powder, salt, and spices and mix on low speed until just combined. Add in oats and mix on low speed, stirring by hand a few times to evenly incorporate the oats.
- Assemble the strawberry rhubarb oatmeal bars. Press 3/4 of the dough mixture evenly into the foil-lined baking pan. Place the remaining quarter of the dough mixture into the freezer for 10-15 minutes.
- Spread the fruit compote over the layer of pressed dough, spreading evenly over the surface with a rubber spatula. Crumble the remaining chilled dough over the top of the fruit.
- Bake the bars. Bake for 50-60 minutes, until the crumble layer is golden brown. Cool completely in the pan on a wire rack.
- Remove from the pan using the foil handles. The bars are heavy, so the center may require support from a spatula – it will start to sag when lifted by the foil alone. Slice into 18 large bars or 24 squares.
- Optional: serve with blueberry sauce and freshly-whipped cream. Combine all ingredients for the blueberry sauce in a small, heavy-bottomed saucepan over medium heat. Bring mixture to a boil, stirring constantly. Cook for 2-3 additional minutes, stirring occasionally, until the sauce is thickened. Serve warm or at room temperature. Top with whipped cream.
Strawberry rhubarb oatmeal bars can be stored in an air-tight container at room temperature for up to 2 days. For longer storage, refrigerate for up to 5 days or freeze for up to 3 months. Place a piece of parchment paper or wax paper between layers of bars to prevent them from sticking to each other.