Step 1

Coat a 9- x 13-inch baking dish with cooking spray. Add batter and bake according to package directions; let cool.

Step 2

Using the end of a wooden spoon, poke holes about 1 inch apart all over top of cake. Reserve 2 tablespoons condensed milk in a small bowl; pour remainder over top of cake and into holes.

Step 3

In a large bowl, beat mascarpone, ricotta cheese, and vanilla until creamy. Beat in confectioners' sugar and reserved condensed milk until smooth. Spread frosting evenly over top of cake. Sprinkle with chocolate chips.

Step 4

Refrigerate cake 2 hours, or until ready to serve.