Preheat oven to 350 degrees. Lightly butter and flour 8×8 in pan.
Cream the butter, white sugar, and dark brown sugar. Add the egg and mix again. Add baking soda (dissolve with 1 tsp hot water), pure vanilla extract, and kosher salt. Beat 1-2 minutes until creamy and fluffy. Add the flour and mix until incorporated.
Spread mixture in prepared 8×8 pan until even. Sprinkle the chocolate chips on top of the spread mixture.
Bake for 5 minutes to melt the chips. Remove from oven and using a butter knife "swirl" the chocolate throughout the batter (go up, down and then across). Return to oven and bake for an additional 16-17 minutes. Bars will still look a little soft when you remove them, don't overbake!
This recipe may be easily doubled and put in a 9×13 pan, as well. Enjoy!
Recipe submitted by Debra and Will Schreiber, Mill Valley, California