Butter and flour a 13x9 inch pan. In a large mixing bowl, beat 1 yellow cake mix, 3 large eggs, 1 cup buttermilk, 1 cup mashed ripe banana, 1/2 cup firmly packed brown sugar, 1/2 cup vegetable oil, and 1/2 tsp. ground cloves on low speed just until moistened. Beat at medium speed for 2 minutes. Fold in 1 cup toasted pecans, pour into pan. Bake 35-38 minutes at 350.
In small saucepan, melt 3 Tbsp. each of butter and packed brown sugar. Add 3 Tbsp. heavy cream and simmer 1 minute. Remove from heat; whisk 2/3 cup confectioners sugar and 1/2 tsp. vanilla extract until smooth. Spread glaze over cake; sprinkle with 3/4 cup chopped milk chocolate butter toffee bars and 1/2 cup chopped toasted pecans.
