Preheat the oven to (350°F) = (176°C) degrees.
Grease a large cookie sheet ( approx. 12 inches by 16 inches).
Cream the butter, white sugar, and brown sugar, then add the eggs and continue to cream the mixture.
Add the rest of the ingredients (except the chocolate chips) and blend until smooth.
Spread the peanut butter mixture onto the greased cooked cookie and bake for 10 minutes.
After baking, turn the oven OFF, and quickly sprinkle the chocolate chips over the bars and return the pan to the oven to melt the chocolate.
After 2 minutes remove the pan again and smooth the chocolate chips evenly across the peanut butter bars.
Let them set up overnight before cutting, preferably.
You can also place the pan in the refrigerator to set the mixture quicker after letting it cool for a few minutes.
Once the chocolate chips and the peanut butter bars are set, you can cut them into squares.