In a medium-sized bowl, add the flour, salt and baking soda. Mix to combine. Set aside.
In the bowl of a stand mixer, add the brown sugar, granulated sugar and softened butter. Mix until creamy.
Add the eggs and vanilla extra. Mix until creamy and without clumps.
Gradually add in the flour and mix until a thick batter forms.
Chop the pretzels into smaller pieces.
Add the chocolate chips, red and green M&Ms and the chopped pretzels. Mix on medium speed until combined. (Reserve a few M&Ms to press into the top of the cookies after baking)
Place the mixing bowl in the refrigerator and chill for one hour.
Preheat the oven to 350°F.
Using a small cookie scoop, scoop out the cookie dough. Roll into balls and place on baking trays lined with parchment paper or sprayed with non-stick baking spray.
Cook for 8-13 minutes or until the cookies are golden brown.
Remove the baking trays from the oven and immediately add a few extra M&Ms to the tops of the cookies pressing slightly.
Allow the cookies to cool for a few minutes on the baking trays and then transfer them to a baking rack to cool completely.
Notes
Chill the cookie dough before baking. You have two options: you can either chill the dough in the mixing bowl, or scoop the dough onto the baking trays and refrigerate them for at least 1 hour.