Make the filling: Combine cherries, sugars, cornstarch, salt, and water in a saucepan over medium heat. Cook, stirring occasionally, until thick and glossy, about 8 to 10 minutes. Remove from heat and stir in vanilla and almond extract.

Make the topping: Preheat oven to 375°F (190°C). Grease a 9x13-inch baking dish. In a large bowl, whisk together flour, sugars, baking powder, and salt. Cut in cold butter until mixture resembles coarse crumbs. Stir in milk and vanilla until just combined — do not overmix.

Assemble: Pour cherry filling into the baking dish. Drop topping by heaping spoonfuls over the filling. Sprinkle with coarse sugar if desired.

Bake: Bake for 35 to 45 minutes until the topping is golden brown and the filling is bubbling at the edges.

Cool and serve: Rest for 10 to 15 minutes before serving. Serve warm with vanilla ice cream or whipped cream.