Preheat the oven to 375°F. In a large bowl, mix together peaches, blueberries, sugar, cornstarch, lemon juice, zest, vanilla, cinnamon, and a pinch of salt. Let it sit for at least 10 minutes.

Meanwhile, make the topping: In another large bowl, whisk together flour, sugar, baking powder, and salt. Add cold butter and use your hands to incorporate it into the flour until pea-sized. Stir in buttermilk until just combined.

Pour the fruit filling along with all the juices into a 9”x13” pan. Drop large spoonfuls of topping evenly over the fruit.

Bake until the top is golden and the peaches are tender, about 45 minutes. Let it cool for 15 minutes before serving. Enjoy!