Pour the warm butter into the bowl of your stand mixer (or a large bowl for a hand-held mixer, or to mix manually).

Add both sugars and salt. Mix on medium speed ONLY until the butter and sugar mix together. It’s OK if the mixture is separated. DO NOT over-mix, because if you cream the mixture or add too much air, the cookie will have a more cakey texture.

Add the vanilla and eggs, and mix until just mixed through. The batter should be smooth and emulsified at this point.

In a separate bowl - sift the flour, both cocoa powders, baking soda, and baking powder together. Add the dry ingredients in two additions, while the mixer is on the lowest speed. This is to prevent the flour from flying everywhere and making a mess, and also to prevent the dough from being over-mixed. The flour doesn’t have to be completely mixed in before adding more.

When most of the flour is mixed in, add the chocolate chips / chunks, and mix on low speed until the chocolate chunks / chips are mixed through. I prefer to do this step by hand with a spatula.

Remove the bowl from the mixer, and mix the dough just a few times by hand. This is to ensure the bottom of the bowl is mixed well with the rest of the dough. Let the mixture rest for at least 20 -30 minutes, covered.

Using a 3 tbsp cookie scoop, portion the cookie dough on a parchment paper-lined half sheet pan. Stud the cookie mounds with the M&Ms. You can add about 6 - 8 M&Ms, so that they spread out as the cookies spread while they bake.

Cover the sheet pan with plastic wrap and let the cookie dough chill overnight (or at least 1 hour). They can also be frozen at this point.

Preheat the oven to 350°F / 180°C. Line a half sheet pan with parchment paper. Place 4 - 6 cookie dough portions on one half sheet pan, evenly spaced apart.

Bake in the preheated oven for 12 - 15 minutes. I like to bake the cookies for 14 minutes for a chewier texture, and 12 - 13 minutes for a softer result. The bake time should be extended by about 1 - 2 minutes if you're baking the cookies from frozen. Rotate the pan once half way through the baking time.

Remove the cookies from the oven, and carefully stud the cookies with candy monster eyes. Gently press them in to the warm cookie to make sure they are secure and don’t fall off.

Let the cookies cool down on the pan for about 6 - 10 minutes. Then carefully place the cookies on a cooling wire rack to let them cool down further.

The cookies can be eaten warm or at room temperature.

Unbaked cookie dough - Place the chilled cookie dough portions in a gallon-sized ziploc bag or an air-tight container, and store in the freezer. When you're ready to enjoy them, remove portions of cookie dough from the freezer and bake for 14 - 17 minutes at 350°F.

Baked cookies - Place one layer of chocolate chip cookies on the bottom of an air-tight container, followed by parchment paper or 2 - 3 tortillas, and then another cookie layer. Repeat with all the cookies (using parchment paper or tortillas). Replace the tortillas every 2 days or so (when the tortillas look like they are drying out). Baked cookies can be kept up to 3 - 5 days at room temperature.

To freeze baked cookies, layer them in an air-tight container using parchment paper. Let them thaw out, OR slightly warm the cookies in the oven before enjoying them.