Preheat oven to 350 degrees F.

Cream sugars and the melted butter with an electric beater on low until completely combined. If you have un-melted pieces of butter in the liquid butter, don't worry, it'll melt down in the mixture.

Add the egg and vanilla until just beaten in (about 10 seconds), do not over mix.

Mix the flour, baking soda, and salt into the wet ingredients with a silicone spatula until the flour is just incorporated. It should kind of come together into one soft mass that is easy to manipulate with your hands without being gooey and sticky.

Toss in all the M&M's and chocolate chips and use a spatula or your hands to mix them into the dough.

Use a cookie scoop to make even cookie balls and place them onto a baking sheet lined with parchment paper. Bake each batch for 10 minutes. Do not over bake! It's better to pull out early than to pull out late! They should be very puffy looking, even a little pale when taken out.

Let them cool for 5 minutes on the pan, then allow them to cool for 15 minutes on a cooling rack.

Keep in an air tight container and they'll stay fresh for at least 3-5 days.