Preheat oven to 350 degrees. Grease a 13x9 inch baking pan. Whisk together the mashed bananas, sugar, milk,oil, cinnamon and eggs in a large bowl. Make sure everything is incorporated well. Using a wooden spoon stir in the 2 2/3 cup baking mix and 3/4 cup chopped pecans. Fold the banana slices into the batter, pour the batter into the prepared pan. Streusel Topping:Place the baking mix, brown sugar and cold butter into a medium bowl. Cut the butter into the baking mix with a pastry blender, add 1/2 cup chopped pecans. Stir to incorporate the nuts. Sprinkle the streusel over the cake batter evenly. Bake 35 - 40 minutes or until tests done with a toothpick.