In a separate bowl, stir together the sugar, flour, baking powder, and salt for the topping. ½ cup 100 g granulated sugar ¾ cup 90 g all-purpose flour ¾ teaspoon baking powder Pinch salt
Mix in the melted butter plus the vanilla extract until it comes together into a thick, crumbly dough. 1 teaspoon vanilla extract 6 tablespoons (85 g) unsalted butter, melted
Break the topping into small pieces and scatter them over the blueberries. It doesn’t have to be perfect — some gaps are good because the fruit can bubble through.
Bake on the center rack for 35-40 minutes or until the topping is golden and the filling is bubbling around the edges. Remove from the oven, place on a cooling rack, and allow to cool for at least 5 minutes before serving. Serve warm with vanilla ice cream! Cover leftovers tightly and store in the refrigerator for up to 4 days.