This is a huge recipe. So we are going to bake the brownies in a rimmed cookie sheet (18X13 inches). Line the cookie sheet with parchment paper and set aside.

Preheat the oven to 300 F.

Whisk together the flour, salt and baking soda. Set aside.

Combine the butter with 1/2 cup of the chocolate chips in a microwave safe bowl. Melt, in 30 second intervals on 50% power until you can whisk it smooth.

Whisk in the sugars and cocoa powder.

Add the eggs one at a time, stirring vigorously after each one. Beat in the vanilla. When the batter looks thick, shiny, and well blended, add the flour mixture and stir until you cannot see it any longer, then beat vigorously for about 40 strokes. Stir in the oats, both kinds, and then fold in the remaining chocolate chips and 1 cup of the M&Ms. Spread the batter evenly in the prepared pan. Sprinkle with the remaining 1/4 cup of M&Ms and then sprinkle with vanilla salt to taste.

Bake until a toothpick plunged into the center emerges slightly moist with batter, about 35 minutes. Let cool completely on a rack.

Using a biscuit cutter, cut the brownies into rounds (or slice into rectangles). Be sure to enjoy the scraps if you use the biscuit cutter!