Blueberry Picnic Bars Recipe (Oat Crumb Bar Cookies)
This blueberry picnic bars recipe is a portable bar cookie with an oat-and-brown-sugar crumb base and a lemon-bright blueberry filling. You’ll mix a simple crumble, quickly cook the berries just until thickened, then bake it all in layers. Let it cool fully so the bars slice cleanly.
Ingredients
Ingredients
Step-by-Step Method
Preheat and prep the pan
Heat the oven to 350°F (175°C). Grease a 8-inch (20 cm) square pan or line it with parchment, leaving a bit of overhang for easy lifting.
Mix the dry ingredients
In a bowl, combine oats, flour, brown sugar, baking soda, and salt. Break up any sugar lumps with your fingers.
Add fats to make a crumb
Pour in the melted butter and the margarine. Stir until you get a sandy mixture that holds together when pressed.
Press in the base
Set aside about 1/3 of the crumble for the top. Press the remaining 2/3 firmly into the bottom of the pan in an even layer.
Cook the blueberry filling briefly
In a small saucepan, stir together blueberries, sugar, cornstarch, and lemon juice. Cook over medium heat for 3–5 minutes, stirring, just until slightly thick and glossy.
Assemble the layers
Spread the blueberry mixture over the crust. Sprinkle the reserved crumble evenly on top; it’s fine if some blueberry shows through.
Bake
Bake for 40–42 minutes, until the top is lightly golden and the edges look set.
Cool and slice
Cool completely on a rack before cutting into 16 bars. For extra clean cuts, chill for 30 minutes first.