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.