Toffee Coffee Cake 1/2 cup butter or margarine, softened 1 cup firmly packed brown sugar 1/2 cup granulated sugar 2 cups all-purpose flour 1 cup buttermilk 1 egg 1 teaspoon baking soda 1 teaspoon vanilla extract 3 (1.4 ounce) chocolate English toffee candy  bars     (such as Heath® bars), chopped 1/4 cup chopped pecans In a mixing bowl, blend butter, sugars and flour; set aside 1/2 cup. To the remaining butter mixture, add buttermilk, egg, baking soda and vanilla extract; mix well. Pour into a greased and floured 13 x 9-inch baking pan. Combine chopped candy and pecan with the reserved butter mixture; sprinkle over coffee cake. Bake at 350 degrees F for 30 to 35 minutes or until a wooden pick inserted near the center comes out clean. Cool on a wire rack.