Preheat oven to 350. Grease bottom of 8-inch baking pan.
Melt butter and chocolate in medium saucepan over low heat, stirring occasionally. Stir in sugar. Add eggs, one at a time, beating after each addition. Stir in vanilla. Combine flour, baking powder and salt; add to chocolate mixture, stirring until well blended. Spread batter in prepared pan.
Bake 20 minutes or until brownie begins to pull away from sides of pan. Remove from oven; sprinkle with toffee bits. Cover tightly with foil. Cool completely in pan on wire rack. Remove foil; cut into squares.