01 -
Position a rack in the center of the oven and preheat to 375°F (190°C). This moderate temperature allows the fruit to cook through and bubble while the topping gets golden and crisp.
02 -
In a medium bowl, gently combine the fresh blueberries, diced peaches, light brown sugar, lemon juice, and cornstarch. Toss everything together until the fruit is evenly coated with the sugar and cornstarch mixture. The cornstarch will help thicken the juices released by the fruit as it bakes, while the lemon juice brightens the flavors and helps prevent the peaches from browning. Spread this fruit mixture evenly into an 8x8-inch square baking dish.
03 -
In a food processor, combine the chopped pecans, cold cubed butter, ground cinnamon, brown sugar, all-purpose flour, and salt. Pulse 2-3 times to begin incorporating the ingredients. The mixture should still be quite coarse at this point. Add the rolled oats and pulse an additional 2-3 times. The crumble should be chunky and uneven with visible bits of butter throughout; be careful not to over-process, as this would create a paste rather than a crumbly texture.
04 -
Sprinkle the oat and pecan crumble mixture evenly over the prepared fruit in the baking dish. Cover the entire surface of the fruit, but don't press the topping down—keeping it loose allows for better browning and a crispier texture.
05 -
Bake in the preheated oven for 25-35 minutes, or until the crumble topping turns golden brown and the fruit filling is bubbling around the edges. If you notice the crumble starting to brown too quickly (usually around the 25-minute mark), loosely tent the baking dish with aluminum foil to prevent over-browning while allowing the fruit to continue cooking. The total baking time may vary depending on the juiciness of your fruit and your oven's peculiarities.
06 -
Remove the crisp from the oven and place it on a cooling rack. Allow it to cool for at least 5 minutes before serving; this brief cooling period allows the filling to set slightly and makes serving easier. For the ultimate experience, serve warm with a scoop of vanilla ice cream, which creates a delicious contrast of warm fruit and cold, creamy ice cream.