Beat egg yolks and sugar until light. Add almonds. Beat egg whites until stiff. Fold egg whites into egg yolk mixture.
Line a 13 x 9 inch baking pan with waxed paper. Pour batter into the pan. Bake in a 325F oven for 12 to 15 minutes.
Remove from the pan and cool. Cut into small squares.
To make blueberry sauce, puree 1/2 cup blueberries in a food processor or blender. Dissolve cornstarch in cream. Cook cream, remaining blueberries, and blueberry puree over low heat until thickened, about 5 minutes. Cool. Stir in sugar substitute.
To serve, line a serving dish with 1/2 of blueberry sauce; arrange cake squares over blueberry sauce. Top with remaining sauce. Spoon on yogurt. Serve immediately.