Combine 1/3 cup butter and powdered sugar in bowl; beat at medium speed until well mixed. Add ground almonds, 1/8 teaspoon salt, 1 egg yolk, milk and 1/2 teaspoon almond extract; continue beating until well mixed. Add flour; beat at low speed until well mixed.
Shape dough into ball; flatten slightly. Wrap in plastic food wrap. Refrigerate 1 hour until firm.
Heat oven to 400°F.
Roll out dough on lightly floured surface into 10-inch circle. Place into 9-inch tart pan with removable bottom or 9-inch glass pie pan, pressing dough into bottom and up sides. Trim crust even with edge; prick crust all over with fork. Bake 10 minutes.
Reduce oven temperature to 350°F.
Combine 1/2 cup sugar, brown sugar, cornstarch and cornmeal in bowl; mix well. Add all remaining filling ingredients; mix well. Pour filling into partially baked crust. Bake 30-35 minutes or until center is set and top is golden brown. (Cover edges of crust with aluminum foil during last 15 minutes of baking.) Remove tart to cooling rack; cool to room temperature.
Combine orange juice and 2 tablespoons sugar in bowl; stir until sugar is dissolved. Combine berries and mint in bowl; toss lightly. Pour orange juice mixture over berries; let stand 30 minutes.
Cut tart into individual servings; top each serving with berry compote mixture. Garnish with whipped cream and sliced almonds, if desired.
*Substitute 2 teaspoons vinegar or lemon juice and enough milk to equal 3/4 cup; let stand 5 minutes.