Preheat oven to 425°. Grease 6 (6-oz.) ramekins or individual soufflé dishes with 1 Tbsp. butter.
Microwave 1 cup butter and chocolate morsels in a microwave-safe bowl at HIGH 2 minutes or until chocolate is melted and mixture is smooth, whisking at 1-minute intervals.
Beat egg yolks and eggs at medium speed with an electric mixer 1 minute. Gradually add chocolate mixture, beating at low speed until well blended.
Sift together sugar, flour, and salt. Gradually whisk sugar mixture into chocolate mixture until well blended. Whisk in coffee liqueur. Divide batter among prepared ramekins. Place ramekins in a 15- x 10-inch jelly-roll pan.
Bake at 425° for 14 to 16 minutes or until a thermometer inserted into cakes registers 165°. Remove from oven, and let stand 10 minutes. Run a knife around outer edge of each cake to loosen. Carefully invert cakes onto dessert plates. Garnish, if desired.
Note: For testing purposes only, we used Ghirardelli 60% Cacao Bittersweet Chocolate Chips and Kahlúa for coffee liqueur.