Step 1

Prepare a 9x9 pan by spraying lightly with pan spray and lining with a parchment sling cut to fit the pan. Set aside. Preheat the oven to 325℉

Step 2

Melt the butter in the microwave for 45-60 seconds, then add the brown sugar, eggs and vanilla extract. Stir together until everything is combined.

Step 3

Add the flour, baking powder, baking soda, and salt. Stir until everything is well incorporated and no flour streaks remain.

Step 4

Fold in half of the chocolate chips and the walnuts, if using. Pour the batter into the prepared pan, smoothing to the edges. Sprinkle the remaining chocolate chips on top of the dough.

Step 5

Bake at 325 ℉ for 40-45 minutes or until a toothpick inserted in the center comes out clean.

Step 6

Let cool completely before slicing into 12 bars.