Pre-heat oven at 350F.
Line baking tray with parchment paper or silicon mat.
Everything should be at room temperature for this recipe like eggs and butter. Make sure butter in softened. Leave butter at room temperature for 15 minutes to 30 minutes. Cold ingredients don’t combine very well.
Use stand mixer or hand mixer to make cookie dough.
Into a large bowl add softened unsalted butter, granulated sugar and light brown sugar.
Beat until creamy.
Add creamy peanut butter, beat to combine. Do not over beat.
Crack egg to the bowl, beat to combine.
Add vanilla extract, beat until just combined.
Add all-purpose flour, baking soda, salt and ground cinnamon.
Beat to combine. Scrape the sides of the bowl in between and continue mixing.
Once dough comes together using silicon spatula fold quick oats (note I used rolled oats), semi-sweet chocolate chips and mini M&M’s.Tip: cookie dough should be non-sticky and easy to handle. If dough is very soft and sticks to the hand, cover with dough with cling film and chill in refrigerator for 30 minutes. Scoop 2 tablespoons of dough mix and place on baking tray lined with parchment paper or silicon mat.
Lightly roll the dough into even shaped balls.
Place extra M&M’s on top for look. This step is optional.
Lightly press down the balls to flatten a bit.
Bake in pre-heated oven at 350F for about 11-13 minutes.
You don’t want cookie to brown. When cookies come out of the oven it will looks still soft.
Let cookies cool on the tray for 10 minutes.
Carefully transfer to wire rack and cool completely.
Cookies will firm as they cool.
Serve monster cookies right away or store in air tight containers at room temperature for about a week.