Chocolate Coffee Tiramisu

Use a 9 inch square baking dish sprayed with vegetable spray. In a food processor, combine ricotta cheese, light cream cheese, first measure of sugar, cocoa, egg yolk, and vanilla until smooth. Transfer to bowl. In another bowl beat egg whites until soft peaks form. Gradually add second measure of sugar and continue to beat until stiff; gently fold the whites into the ricotta mixture. Combine coffee and liquer. Put the lady fingers in bottom of a dish sprinkle with half of the coffee- liquer mixture; spread half of ricotta mixture on top; repeat layers, cover and chill for at least 3 hours, or overnight.