Sift flour, baking cocoa, 1/4 cup sugar and salt into food processor container. Add 3/4 cup butter and process til crumbly. Add coffee gradually, processing til mixture forms a ball. Knead on lightly floured surface 4 to 6 times. Shape into a log. Chill, wrapped in plastic wrap for 6 hours or longer. Divide chilled dough into 4 portions. Roll one portion into a 14 to 15 inch circle 1/8 inch thick on lightly floured surface, keeping remaining portions refrigerated. Cut into 3 inch circles. Press each circle into a greased miniature muffin cup. Repeat with remaining dough.
Mix the melted chips, 2/3 cup sugar, 2 Tbsp. butter, milk and coffee liqueur in a bowl. Add eggs and beat til smooth. Stir in walnuts.
Put 1 rounded teaspoonful into each prepared muffin cup. Bake at 350 for 20 to 25 minutes or til filling is set. Cool in pan for 15 minutes. Remove to wire rack to cool completely. Makes 4 dozen.