1. In a large mising bowl beat butter with an electric mixer on medium to high speed 30 seconds or until softened. Add sugar and baking powder. Beat until combined. Beat in eggs and vanilla until combined. Beat in cocoa powder and as much flour as you can with the mixer. Stir in chocolate pieces and walnuts. Divide dough in half.

2. Lightly grease a cookie sheet. Shape each portion into 9x2x1 inch loaf. Place the loaves 4 inches apart on prepared cookie sheet. In a small bowl stir together the egg yolk and milk. Brush mixture over loaves. Bake in a 375 degree F oven for 25 minutes. Cool on cookie sheet for 30 minutes.

3. Cut each loaf diagonally into 1/2 inch thick slices. Lay slices cut side down on cookie sheet. Bake in a 325 degrees F oven 15 minutes. Turn slices over. Bake 10 to 15 minutes more or until dry and crisp. Remove from cookie sheet and cool on a wire rack. Store in an airtight container at room temperature for up to 3 days.

I hope you all enjoy these biscotti, I did!!