Cream Cheese Swirl Brownies

I love these brownies!!! They're fun to make, but I had to wait until cream cheese went on sale to make them. I got the recipe online.
Cream Cheese Swirl Brownies

Filling:
4 oz cream cheese (1/2 package)
1 egg
3 tablespoons sugar
1/4 teaspoon vanilla

Brownies:
Brownie mix and all that goes with it

Heat oven to 350 degrees F. Grease bottom only of 9-inch square pan. beat filling ingredients in a small bowl. Set aside.
Make brownie batter as directed on box. Spread 3/4 of batter in pan. Spoon filling onto batter. Add remaining batter. Cut through mixture with a knife for marbled design. Sprinkle with chocolate chips if desired.
Bake 40-44 minutes. Cool. Store in fridge.