1. Preheat oven to 350 degrees F. Line 8 x 8 x 2-inch-square baking pan with aluminum foil; generously grease the foil.
2. Combine flour, baking powder and salt in medium-size bowl.
3. Melt the butter in a medium-size saucepan. Remove the saucepan from the heat. Stir in the brown sugar and the granulated sugar until well blended. Cool the mixture slightly. Stir in the egg and vanilla.
4. Stir the flour mixture, walnuts and toffee bits into the butter mixture in the saucepan just until incorporated (the mixture will be stiff). Spread the batter evenly with a rubber spatula in the prepared pan.
5. Bake in preheated 350 degree F oven for 35 to 40 minutes or until the blondies begin to pull away from the sides of the pan. Place the pan on a wire rack and let cool completely. Cut the blondies into sixteen 2-inch squares. Makes 16.