Preheat oven to 350 F / 177 C / gas mark 4. Grease 8x8 inch baking pan. (Or line with parchment paper)
Combine flour, baking soda, and salt in a small bowl. Combine melted butter and sugars in a large bowl. Add eggs and vanilla and whisk until combined. Pour the flour mixture into the butter/sugar mixture and stir just until combined. Stir in chocolate chips.
Spread dough into prepared baking pan. Make sure to spread into edges of pan.
Bake at 350 for about 30-35 minutes, or until edges are set and toothpick inserted into center comes out clean. Let cool for about 20 minutes before cutting.