Preheat the oven to 350°F (175°C) and lightly grease a 9x9-inch baking dish.

In a large mixing bowl, combine sliced peaches, blueberries, granulated sugar, brown sugar, cornstarch, lemon juice, vanilla extract, and cinnamon. Toss gently until the fruit is evenly coated.

Pour the fruit mixture into the prepared baking dish and spread it evenly.

In another bowl, combine flour, oats, brown sugar, cinnamon, and salt.

Pour in the melted butter and stir until crumbly clusters form throughout the mixture.

Sprinkle the crumble topping evenly over the fruit filling, covering the surface completely.

Bake for 40–45 minutes, or until the topping becomes golden brown and the fruit filling bubbles around the edges.

Remove the crumble from the oven and let it cool for about 10–15 minutes before serving.

Serve warm with vanilla ice cream or whipped cream if desired.