- For the Blueberry Layer
- 2 cups fresh or frozen blueberries
- 2 teaspoons cornstarch
- Zest of one lemon (about 1 tablespoon is plenty)
- 1 tablespoon freshly squeezed lemon juice (don't use bottle lemon juice - it's too tart)
- ¼ cup granulated sugar
- For the Bottom Lay & Top Crumble
- 1 and ¼ cup all-purpose flour, spooned & leveled (GF use Domata)
- ½ cup granulated sugar
- ½ teaspoon baking powder
- 10 tablespoons unsalted butter, cold (1/2 cup plus 2 tablespoons)
- 1 large egg yolk
- 1 tablespoon packed brown sugar
- 1 tablespoon granulated sugar
- Preheat the oven to 375F degrees.
- Line an 8x8 inch square baking pan with aluminum foil leaving an overhang on each side and grease with butter. Set aside.
- To make the blueberry mixture, in a medium bowl toss together all the ingredients (blueberries, cornstarch, lemon zest, lemon juice & sugar) until the blueberries are covered. Set aside.
- In a separate large bowl whisk together the butter, flour, ½ cup granulated sugar & baking powder. Cut in the butter & egg yolk using a pastry cutter or fork until the mixture is crumbly and resembles wet sand.
- Press about two thirds to three quarters of the mixture into the bottom of the prepared pan and pack it down tightly with your hands. Pour the blueberry mixture over top.
- To the remaining flour mixture, cut in the brown sugar and remaining 1 tablespoon of granulated sugar. Crumble the remaining dough over the blueberry mixture by squeezing it in a fist with your hand, then crumbling it over the mixture.
- Bake in the oven for about 45 minutes, until you see the blueberries bubbling and the crumble layer starting to turn golden. Allow to cool fully to room temperature . Then lift the bars out of the pan using the aluminum foil overhang and cut into squares. I cut mine into 9 large bars.
- Bars are best stored in an air tight container in the fridge.