Adjust one rack to divide the oven in half. Preheat the oven to 350. Lightly grease and flour a 12-inch pizza pan. In a large bowl, beat the butter and sugars until light and creamy, 2-3 minutes. Beat in the egg and vanilla until well blended. With the mixer at medium-low speed, gradually add the flour, beating just until blended. Spread the dough evenly in the prepared pan. Bake for about 20 minutes until just firm to the touch. Remove from the oven and immediately sprinkle evenly with the chocolate chips, pecan pieces and marshmallows. Return to the oven and bake until the marshmallows are melting and lightly browned, about 15 minutes. Reverse the pan from front to back once during baking. Set the pan on a wire rack and cool for about 10 minutes. WIth a long, serrated knife, cut the pizza into 12 wedges. Serve warm or cool. Yield 12 cookie wedges Recipe by: The Cookie Book, by Holly Garrison Posted to MC-Recipe Digest V1 #1010 by "marcia.bales@sierra.com" on Jan 14, 1998