Blueberry Oatmeal Crumble Bars

Crust and Crumble Topping

unsalted butter, melted

all-purpose flour

old-fashioned whole-rolled oats (don’t use quick cook or instant, they’re finer and behave like flour and will make mixture too dry)

granulated sugar

light brown sugar, packed

salt, optional and to taste

Blueberry Layer

blueberries (fresh or frozen; I used frozen and didn’t thaw)

granulated sugar

lemon juice

cornstarch