1 1/2 cups (11.25 ounces) packed light brown sugar
1 tablespoon vanilla extract
2 cups (10 ounces) all-purpose flour
1 teaspoon baking soda
1/2 teaspoon salt
2 cups (12 ounces) chocolate chips
Preheat the oven to 350 degrees F. Line a 9X13-inch metal baking pan with foil (the foil part is optional but helps the bars come out in one big slab after cooling and provides easy clean-up). Spray the foil with nonstick cooking spray. Set aside.
In a large microwave-safe bowl, melt the butter. Whisk in the peanut butter, eggs, brown sugar and vanilla extract.
Gently stir in the flour, baking soda and salt until just combined. Add the chocolate chips and stir until no dry streaks remain and the chips are evenly combined.
Press the dough evenly in the prepared pan. Bake for 20-25 minutes until set in the middle and lightly browned on the edges. Don’t overbake! We're going for soft and delicious here. Let cool completely in the pan before cutting into squares.
I've only ever used creamy peanut butter like Jiffy or Skippy and not natural peanut butter (or another nut butter), but you could experiment.