2 (1 ounce) squares semisweet chocolate
3/4 cup butter (at room temperature)
1/2 cup firmly packed light brown sugar
1 1/2 cups all-purpose flour
Melt chocolate in the top of a double boiler over hot water or in microwave oven; set aside.
In a large mixing bowl at medium speed of electric mixer, beat butter until fluffy. Add brown sugar; beat until very light and fluffy. Reduce mixer speed to low, then blend in melted chocolate, then flour.
Spread dough evenly in an ungreased 8-inch square baking pan. Prick surface with fork tines. Bake at 350 degrees F for 20 to 25 minutes, or until wooden pick inserted in center comes out clean.
Let cool in pan on rack for 10 to 15 minutes, then cut into squares.