How to Make It
In a 2- to 3-quart pan over low heat, frequently stir butter and 1 cup chopped white chocolate until melted and smooth. Remove from heat and stir in sugar, eggs, vanilla, and flour until well blended.
Spread batter evenly in a buttered and floured 8-inch square baking pan. Sprinkle toffee bits and remaining 1/3 cup white chocolate evenly over the top.
Bake in a 350° oven until edges feel firm to touch and begin to turn a shade darker, 25 to 30 minutes.
Run a knife between pan rim and brownie. Let cool in pan on a rack, about 1 hour. Cut into 9 or 16 squares.
Note: Nutritional analysis is per small brownie.