Nanaimo Bars: Butter or spray a 9 x 9 inch (23 x 23 cm) pan with a non stick vegetable spray.
Bottom Layer: In a saucepan over low heat, melt the butter. Remove from heat and stir in the sugar and cocoa powder and then gradually whisk in the beaten egg. Return the saucepan to low heat and cook, stirring constantly, until the mixture thickens (1 - 2 minutes). Remove from heat and stir in the vanilla extract, graham cracker crumbs, ฃthe bottom layer, cover, and refrigerate until firm (about 30 minutes).