1/2 cup unsalted butter, cold and cut into small pieces
Preparation
Preheat your oven to 350°F (175°C). Grease a baking dish or individual ramekins.
In a large bowl, combine the frozen blueberries, granulated sugar, lemon juice, and cornstarch. Toss until the blueberries are evenly coated. Transfer the blueberry mixture to the prepared baking dish, spreading it out evenly.
In a separate bowl, combine the rolled oats, flour, brown sugar, cinnamon, and salt. Mix well. Add the cold, cubed butter to the dry ingredients. Use your fingers or a pastry cutter to incorporate the butter into the mixture until it resembles coarse crumbs.
Sprinkle the crumble topping evenly over the blueberry filling.Bake in the preheated oven for 40-45 minutes or until the topping is golden brown, and the blueberry filling is bubbly.
Allow the blueberry crumble to cool for at least 15 minutes before serving. Serve the Blueberry Crumble warm.
