Heat the oven to 350 degrees. Coat a 9-inch spring-form pan with non-stick cooking spray. Whisk the flour and baking powder in a medium bowl. Beat the sugar, sour cream and butter in a large bowl at medium speed for minute. Add the egg and almond extract; beat until well blended. At low speed, slowly beat in the flour mixture until almost combined. Add the buttermilk; beat just until blended. Stir in 1 cup of the strawberries; spread the batter into the pan. Sprinkle with the remaining strawberries and sliced almonds. Bake for 55 to 60 minutes or until golden brown and toothpick inserted in the center comes out clean. Cool in the pan on a wire rack for 10 minutes; remove sides. Cool completely. Sprinkle with the powdered sugar before serving.