In a mixing bowl with an electric mixer, cream together Butter, Peanut Butter, Sugar, then beat in egg yolk and vanilla extract. Add flour, oats, and wheat-germ and beat the mixture until just combined. Spread the batter evenly into a buttered jelly roll pan, 15 -1/2 x 10-1/2 x 1 inch (40 x 27 x 2.5 cm) smoothing the top, spread egg white, beaten lightly, over batter, and then sprinkle peanuts evenly over it. Bake the mixture in the middle of a pre heated 300 F (150 C) oven for 25 to 30 minutes, or until the top is golden brown. Transfer the pan to a wire rack to cool. While the mixture is still Hot, cut into small even squares and let the cookies cool completely in the pan.