1MIX softened cream cheese and egg until fairly well blended, and then add brown sugar, mix until smooth. the batter will be fairly thin.
2For vamping up a plain batch of brownies, drop tablespoon-fulls of this filling, evenly spaced, throughout your pan of prepared brownie batter, just before putting it in the oven. Some will sink in, some will stay at the top. Bake the brownies as you normally would, adding a few minutes if necessary, to brown the top of the exposed cheesecake filling. Slight cracking of the surface indicates done-ness. The filling will set up as the brownies cool, though hot with a dab of ice cream or frozen yogurt is wonderful!
If you want the filling to be more of a surprise, put 1/3 of your brownie batter in the pan first, then add the cheesecake filling by teaspoonfulls, and then cover with the remaining brownie batter. Bake as usual. If toothpick inserted in center comes out with cheesecake goo, add just a few more minutes to baking time.
3Experiment! This mixture can also be used to make other simple desserts more special - cupcakes, muffins, small tarts, etc. You can use flavorings or colorings, if you wish, but be careful not to thin it down too much.