This peach blueberry crumble has a juicy fruit base with tender peach slices and burst blueberries simmered until glossy, then topped with a buttery, crisp oat crumble. The flavor is bright and balanced, with lemon lifting the fruit and warm cinnamon rounding out the rich, toasted topping.
Store cooled crumble in an airtight container in the refrigerator for up to 3 days. For best texture, store the fruit and crumble topping separately if possible; the topping can be kept at room temperature for 1 day or refrigerated for 3 days. Freeze the fruit filling for up to 2 months; freeze the crumble topping separately for up to 2 months, then thaw overnight in the refrigerator. Reheat the fruit in a small saucepan over low heat for 5 to 7 minutes, stirring gently, and re-crisp the topping on a sheet pan in a 350°F / 177°C oven for 5 to 7 minutes before assembling. If reheating a fully assembled portion, warm in a 350°F / 177°C oven for 10 to 12 minutes, knowing the topping will be slightly softer.