Preheat oven to 400'F

First, make the almond pastry base: Using a stand mixer, beat the egg whites with vanilla, sugar and cream of tartar until they form stiff peaks, like for meringue.

Place almonds in a food processor then grind until they resemble a coarse meal. Combine the ground almonds with the flour. Next, gently fold the almond meal and flour mixture into the meringue until they are thoroughly combined.

Next, line a 13"x 9" baking dish with parchment paper. Pour the almond mixture into the baking dish and bake for about 30 minutes, or until a cake tester comes out clean. Remove from oven and place on a cooling rack. Allow the "cake" to come to room temperature, then invert onto a large cutting board.

To prepare the filling: In a double boiler heat cream and sugar. Slowly add in the beaten yolks while whisking. Then,stir in the almond extract and slowly stir in the unsalted butter until it all melts into the custard.

Next, transfer the custard to a bowl and place in the refrigerator for about 1-2 hours.

Toast the almonds until slightly brown.