Preheat oven to 350 degrees. Spray a 18 x 13 half sheet baking pan (standard sized baking pan) with cooking spray; set aside.
In a large bowl with a hand mixer or a stand up mixer, cream together the butter and sugar until light and fluffy, about two minutes. Add in the eggs and vanilla and mix until combined. Sift in the flour, baking powder, and salt and mix to combine. Fold in the two bags of chocolate chips, save a few for sprinkling over the top of the bars.
Pour the batter into the prepared pan and spread with rubber spatula or damp hands. Sprinkle on the remaining chips. Bake for 20-25 minutes until lightly golden brown. Cool on wire rack completely. Cut into squares.
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Notes
You can easily change the flavor of the bars depending on what types of chips you use. Butterscotch, peanut butter, or dark chocolate chips would all be delicious here.
Bars can be refrigerated in an airtight container for up to a week, or frozen for up to a month.
This recipe can make 40 large bars, 60 medium bars, or 80 smaller bars.