Preheat the oven to 375°F (190°C).
In a medium bowl, combine the brown sugar, flour, oats, butter, cinnamon, and salt. Use your fingers to mix until the topping is crumbly. Set aside.
¾ cup (160 g) dark brown sugar, ½ cup (60 g) all-purpose flour, ½ cup (45 g) old-fashioned oats, ⅕ cup (75 g) butter, 1½ tsps (3 g) ground cinnamon, ¼ tsp (1.5 g) table salt
In a large pot, combine the cherries, raspberries, sugar, water, and cornstarch. Bring to a low simmer over low heat, stirring often. Let simmer for about 10 minutes, gently breaking up some of the cherries as they soften. Remove from heat.
2 lbs. (900 g) fresh cherries, 1½ cups (180 g) fresh raspberries, ¾ cup (150 g) granulated sugar, 1 cup (240 ml) water, 3½ tbsps (28 g) cornstarch
Lightly spray eight 8-ounce (240ml) ramekins—or a 9x13-inch (23x33cm) baking dish—with cooking spray.
cooking spray
Divide the fruit filling evenly among the ramekins, or spread it into the prepared baking dish.
Spoon the oat topping over each ramekin, or evenly across the full surface of the baking dish. If using a 9x13, increase the topping ingredients by half for full coverage.
Place ramekins or baking dish on a baking sheet lined with aluminum foil to catch any bubbling fruit.
Bake for 22 minutes, or until the filling is bubbling and the topping is golden.
Remove from the oven and let sit for at least 20 minutes before serving to allow the filling to set.
Serve warm or at room temperature with vanilla ice cream, if desired.
vanilla ice cream (optional)