Preheat your oven to 350°F (175°C). Line two baking sheets with parchment paper or silicone baking mats.
Cream the Butter and Sugars:
In a large mixing bowl, beat the softened butter, granulated sugar, and brown sugar until light and fluffy.
Add the Wet Ingredients:
Beat in the eggs, one at a time, followed by the vanilla extract until fully incorporated.
Combine the Dry Ingredients:
In a separate bowl, whisk together the flour, baking soda, baking powder, and salt. Gradually add the dry ingredients to the wet mixture, mixing until just combined.
Fold in Mix-Ins:
Gently fold in the M&M’s, white chocolate chips, crushed pretzels, toffee bits, nuts (if using), and sprinkles.
Shape the Cookies:
Scoop about 1 1/2 tablespoons of dough for each cookie and roll into balls. Place them on the prepared baking sheets, spacing them about 2 inches apart.
Bake:
Bake in the preheated oven for 10-12 minutes, or until the edges are lightly golden. The centers will still look soft but will set as they cool.
Cool:
Allow the cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.