Layer in a 1-quart glass jar or canister the following ingredients: brown sugar, chocolate pieces, flour, baking powder, salt, pecans and toffee pieces. Tap jar gently on the counter to settle each layer before adding the next. Cover jar.
Store at room temperature up to 1 month. Or, attach baking directions and gave as a gift.
Grease an 8x8x2-inch baking pan. In a large bowl combine butter, eggs and vanilla. Stir in jar contents. Spread into prepared pan. Bake in a 350 degree F oven for 25 to 30 minutes or until set and golden brown and edges just begin to pull away from pan. Cool in pan on a wire rack. Cut into bars.