1 lb. bitter-sweet chocolate, chopped
1 c. (2 sticks) unsalted butter, cut into tbsp.
1/3 c. espresso or strong brewed coffee
4 lg. eggs, room temperature
1 1/2 c. sugar
1/2 c. flour
2 c. chopped walnuts (optional)

In a 9 x 13 inch pan, make a double thickness of aluminum foil, extend 2 inches beyond sides of pan. Butter foil. Melt chocolate, butter, and coffee. Let cool 10 minutes. Beat eggs; add sugar. Beat until light and fluffy. On low speed, gradually beat in chocolate mixture. Stir in flour (and nuts). Bake 28 to 30 minutes at 375 degrees until just set around edges. They will remain moist in center. Cool in pan on rack for 30 minutes. Cover with foil. Refrigerate overnight or at least 6 hours. Lift out with foil edges. Invert on larger platter. Peel off foil and invert again. Cut into small squares.