Preheat oven to 350 degrees, lightly grease a 13x9 baking pan and set aside
In a large stand mixer combine butter and both sugars until creamed
Next, add in vanilla and eggs.
In a medium-large bowl combine flour, soda, tartar and salt.
Slowly add the flour mixture to the wet ingredients. Be careful not to over mix, beat until just combined.
Fold in chocolate chips, reserving ¼- ½ cup to sprinkle on top.
Pour batter into prepared 13 x 9 pan. Batter will be thick and you may need to use your hands to spread evenly.
Sprinkle batter with remaining chocolate chips.
Bake for 30-35 minutes until golden brown.
Remove from oven and allow to cool before cutting.
Enjoy!