Preheat the oven to 350°F (175°C). Lightly grease a 9x9-inch baking dish.
In a large mixing bowl, stir together 8 cups pitted cherries, ¼ cup lemon juice, ¼ cup granulated sugar, 2 tablespoons cornstarch, ½ teaspoon ground cinnamon, and ½ teaspoon vanilla extract. Transfer to the prepared baking pan, ensuring all juices are included.
In a medium bowl (or using a food processor), mix together 1½ cups all-purpose flour, ¾ cup brown sugar, and ½ teaspoon ground cinnamon. Add the cold, cubed butter and use a pastry cutter (or pulse in the food processor) to combine the mixture. The mixture should be crumbly, with varying sizes of small clumps of butter remaining.
Evenly sprinkle the crumble topping over the cherries in the baking dish, covering them completely.
Bake for 40-45 minutes, or until the crumble topping is golden brown and the cherry filling is bubbling. Serve warm.
Notes
Sweet cherries like Bing or Rainier are the classic choice, while tart cherries like Montmorency will give you a bit more tang.