Coffee Liqueur Brownies

8 (1 ounce) squares unsweetened chocolate
1 cup butter
5 eggs
3 cups granulated sugar
1 tablespoon vanilla extract
1 1/2 cups all-purpose flour
1/2 cup coffee-flavored liqueur
2 cups chopped walnuts

Heat oven to 375 degrees F. Grease a 9 x 13-inch pan.

In a medium heavy saucepan heat butter and chocolate over low heat, stirring constantly. When just melted, remove from heat.

In a large bowl beat eggs, sugar and vanilla extract until thick and pale. Stir in the chocolate mixture and the coffee liqueur. Fold in flour. Stir in walnuts. Spread evenly into the prepared pan. Place on the middle rack of the preheated oven. Bake for 35 minutes.

Remove and let stand for 30 minutes before attempting to cut.