Chocolate Fudge

Melt one tablespoon butter, add one-half cup milk and one and one half cups sugar; stir until sugar is dissolved, then add five tablespoons prepared cocoa, or two squares unsweetened chocolate. Stir constantly until chocolate is melted. Heat to boiling point and boil twelve minutes, stirring occasionally to prevent burning. Extinguish flame, add one teaspoon vanilla, and beat until the mixture is creamy. Pour into a buttered pan, cool, and mark in squares.