1-Preheat your oven and prepare baking dish: Preheat the oven to 350°F (175°C) and lightly butter a 7-9 inch round or 8 inch square baking dish. This ensures easy removal and crisp edges.

2-Prepare the fruit filling: In a large mixing bowl, combine 4 1/2 cups sliced peaches and 1 1/2 cups blueberries with 3 tablespoons of all-purpose flour, 1/3 cup of brown sugar, and 1 tablespoon of lemon juice. The flour helps thicken the juices during baking, while the lemon juice brightens the fruit flavors.

3-Prepare the crisp topping: In another bowl, combine 3/4 cup all-purpose flour, 1/3 cup brown sugar, 1/2 cup old-fashioned oats, 1 teaspoon ground cinnamon, and 1/8 teaspoon salt. Stir in 5 tablespoons of melted unsalted butter until the mixture resembles wet sand.

4-Assemble the crisp: Pour the fruit filling evenly into the prepared baking dish, spreading it out for uniform cooking. Sprinkle the oat topping evenly over the fruit layer, ensuring full coverage to achieve that perfect crispy texture.

5-Bake the crisp: Bake in the preheated oven for 40-45 minutes, or until the topping is golden brown and the fruit filling is bubbly. Consider placing the baking dish on a rimmed sheet pan lined with parchment or foil to catch any overflow and prevent messes.

6-Cool and serve: Allow the Blueberry Peach Crisp to cool for at least 10 minutes before serving. This helps the filling set and makes serving easier. Serve warm with your favorite accompaniment.