Strawberry and Apple Crumble

Name: Strawberry and Apple Crumble
Ingredients: 1/2 pound strawberries, hulled and sliced, plus sliced strawberries for garnish; 1/2 pound cooking apples, like Granny Smith and Jonathan, peeled, cored, and sliced; 3/4 cup granulated sugar; 1/2 cup crushed walnut halves; 1 teaspoon ground cinnamon; 4 pre-baked (4-inch) tart shells, recipe follows; 1 cup plus 2 tablespoons all-purpose flour; 5 tablespoons unsalted butter; 1/2 cup oatmeal; 9 tablespoons packed brown sugar; Confectioners' sugar, for garnish; Serving suggestion: Vanilla ice cream; 9 tablespoons unsalted butter, at room temperature; 1 1/3 cups sifted confectioners' sugar; 2 beaten egg yolks; 1 dash cream; 2 cups all-purpose flour, sifted