Preheat your oven to 350 degrees
Generously butter a 8” or 9” round cake pan and line the bottom of the pan with parchment paper
In a large bowl, combine 10 tablespoons of room temperature butter with 1 large egg, 1 large egg yolk, 2/3 cup of brown sugar, 1/3 cup of granulated sugar and 2 teaspoons of vanilla extract and mix until creamy
Add 3/4 teaspoon baking soda, 1/2 teaspoon kosher salt, 1 3/4 cups of all purpose flour and mix until just combined
Gently fold in 3/4 cup of milk chocolate chips, 1/4 cup of mini M’nM’s, 1/4 cup of toffee bits and 1/4 cup of roughly chopped pretzels
Press the dough evenly throughout the prepared pan
Bake on a center set rack of a 350 degree oven for 22-25 minutes or until the center of the cookie no longer feels sticky to a light touch
Transfer the pan onto a cooling rack and allow the cookie to cool fully before removing from the pan
Garnish with a pinch of sea salt, some chocolate buttercream and sprinkles
Store in an airtight container at room temperature or wrap tightly and freeze