Whisk the flour, cinnamon, nutmeg, salt and baking soda in a medium bowl. Set aside.
In a stand mixer with the paddle attachment or using a hand held mixer, cream the butter for 2-3 minutes until it is very creamy.
Add your two sugars and peanut butter and beat for another 2 minutes.
Add the eggs and vanilla to the dough and mix for another minute. Make sure you scrape down the sides and bottom of the bowl to get all the dough mixed properly.
Add flour mixture to the butter and mix on a low setting until it is thoroughly combined. Fold in your oats and m&ms. The dough is going to be very sticky, so place in the fridge for at least 45 minutes.
Preheat your oven to 350°F/175°C and line 2 baking sheets with parchment paper.
Using a 3 tablespoon cookie scoop, scoop out the dough and make sure you have 3-4 inches between each cookie. Bake them 6 at a time on your cookie sheets for 13-14 minutes.
Allow the cookies to chill for 5 minutes before moving them to a cooling rack.
Notes
My recipes have been developed and tested in metric grams. I highly recommend using a weighing scale and measuring out your ingredients the metric way. I have provided a conversion to US cups but please note that I haven’t tested the recipe with this method.Butter: I use European style butter, like Kerry Gold, in my recipes. This will make your finished bake much creamier and richer.Salt: If you don’t have kosher salt, halve the amount of salt called for in the recipe. 1 teaspoon kosher salt = ½ teaspoon fine salt.Storage: keep the baked cookies in a tupperware for up to 5 days at room temperature. Freeze unbaked cookie dough balls, when ready to bake just bake for an extra minute or two.