Preheat oven to 350 degrees F. If using piecrust mix sticks, crumble into a bowl. Stir in sugar and baking soda. Add egg, milk, and vanilla. Beat with an electric mixer on medium speed until well mixed. Divide in half. Stir cocoa powder and 1/4 cup miniature chocolate pieces into one half; stir strawberry-flavor powder and nuts into the other half. Drop scant teaspoonfuls of each batter, checkerboard-style, into a greased 13x9x2-inch baking pan. Bake for 18 to 20 minutes or until the top springs back when lightly touched. Cool on a wire rack. Cut into diamonds or squares.
In a small, heavy saucepan melt the 1/4 cup chocolate pieces with the shortening over low heat, stirring frequently. Drizzle chocolate over cookies. Makes 36.