Press batter into baking dish and spread evenly throughout. Place in oven to bake for 20-25 minutes, until the middle is cooked through and a toothpick comes out clean. Let cool for 20 minutes before removing from pan.
Melt the remaining mini chocolate chips in a microwave or double boiler then use a spoon to scoop the chocolate and wave the spoon back and forth to spread the chocolate on top of the bars. Slice into 8 bars. Store in refrigerator.