Oaty Mixed Berry Crumble

Name: Oaty Mixed Berry Crumble
Ingredients: 3/4 cup all-purpose flour; 3/4 cup old-fashioned rolled oats; 1 1/4 cups plain granola; 1/2 cup sugar; 1 1/2 sticks (6 ounces) chilled unsalted butter, cut into cubes; 3/4 cup sugar; Finely grated zest of 1 lemon; 1/2 teaspoon cinnamon; 1/4 teaspoon ground allspice; 1/4 teaspoon freshly grated nutmeg; 1 pound blackberries; 3/4 pound blueberries; 3/4 pound raspberries; 2 tablespoons unsalted butter, cut into small pieces; Devonshire cream, vanilla ice cream or lightly whipped cream, for serving