6tablespoonsunsalted buttermelted (or substitute melted coconut oil to make vegan/dairy free)
2cupsfresh blueberries*about 10 ounces
1tablespoon freshly squeezed lemon juicefrom about 1/2 small lemon
FOR THE VANILLA GLAZE (OPTIONAL BUT DELICIOUS, ESPECIALLY IF YOU PREFER A SWEETER BAR):
1/2teaspoonpure vanilla extract
1tablespoonmilkany kind you like
Place a rack in the center of your oven and heat to 375 degrees F. Line an 8x8-inch baking pan with parchment paper so that the paper overhangs two sides like handles.
In a medium bowl, combine the oats, white whole wheat flour, brown sugar, cinnamon, and salt. Pour in the melted butter and stir until it forms clumps and the dry ingredients are evenly moistened. Set aside 1/2 cup of the crumble mixture, then press the rest into an even layer in the bottom of the prepared pan.
Scatter half of the blueberries over the crust. Sprinkle the cornstarch evenly over the top, then sprinkle on the lemon juice and 1/2 tablespoon granulated sugar. Scatter on the remaining berries, then the remaining 1/2 tablespoon sugar. Sprinkle the reserved crumbs evenly over the top. You will have some fruit showing through.
Bake the bars for 30 to 40 minutes, until the fruit is bubbly and the crumb topping smells toasty and looks golden. Place the pan on a wire rack to cool completely (you can speed this process along in the refrigerator).
While the bars cool, prepare the glaze: in a medium bowl, briskly whisk together the powdered sugar, vanilla, and milk until smooth. Feel free to add more milk if a thinner consistency is desired. Using the parchment paper handles, lift the bars from the pan. Drizzle with the glaze, slice, and serve.
*I have not tried this recipe with frozen, thawed blueberries, but I think that it would work. Be sure to thaw the blueberries completely first.
The recipe can be doubled and baked in a 9x13-inch baking pan. The bars will be a bit thicker but still delicious.
To make the bars gluten free, substitute the white whole wheat flour with a 1:1 baking mix like this one.
Store leftovers in the refrigerator for up to 5 days.
To freeze, let the bars cool completely and do not glaze. Wrap tightly in plastic before placing in the freezer. Let thaw in the refrigerator and top with glaze before serving. (Bars can be frozen already glazed if needed.)