Beat butter and brown sugar at medium speed with an electric mixer until creamy. Add egg and vanilla, beating until blended.
Combine flour, baking powder, and salt; gradually add to butter mixture, beating until blended.
Press dough into an ungreased 15- x 10-inch jelly-roll pan.
Bake at 350° for 12 to 15 minutes or until golden. Place pan on a wire rack. Sprinkle chocolate morsels evenly over warm cookie. Let stand 5 minutes; spread chocolate evenly over top. Sprinkle evenly with almonds. Cool completely in pan on a wire rack. Cut into squares.