In a medium bowl, whisk all-purpose flour, sea salt, baking powder and baking soda and set aside.

In the bowl of a stand mixer add sugars and melted butter, you can mix it together with a spatula, then allow it to sit for a couple minutes to absorb some butter into the sugars.

Add eggs and pure vanilla extract and run on medium speed for about 30 seconds.

Mix dry ingredients into the wet ingredients by running on low for about 1 minute with the paddle attachment (I like to do this in two steps because it is a lot of dry goods and prevents it from flying up).

Add chocolate chips to the mixer and run again (I also like to do this in 2 steps for more even distribution). Then fold in MMs – leave some for the top.

Transfer dough to the prepared pan and spread evenly using an offset spatula or your hands (I like to use a pastry roller).

Bake for about 12 minutes or until the edges start to become golden and a toothpick comes out with moist crumbs.

Place tray on a wire rack to cool before slicing. I find it easier to slice in the pan, but you can run the chance of scratching your pan; if you want to remove it you can place a wire rack overtop, then flip it, then place a cutting board on top and flip again.

Slice into any desired sizes.