Preheat your oven to 350°F (175°C). Line two baking sheets with parchment paper – this makes cleanup super easy!
In a large mixing bowl, combine the softened butter, light brown sugar, and granulated sugar. Using an electric mixer, beat them together for about 2 minutes until the mixture is beautifully light and fluffy.
Stir in the egg yolks and vanilla extract or paste. Continue mixing on medium speed for another 2 minutes until the mixture looks pale and even fluffier. This step is key for a great texture!
Gently add the flour, baking powder, baking soda, and salt to the bowl. Mix until just combined, being careful not to overmix the dough.
Now for the exciting part! Add the M&M's, white chocolate chips, crushed pretzel pieces, potato chip pieces, and sprinkles. Gently fold them into the dough with a spatula until everything is evenly distributed.
Scoop the dough into 20 equal-sized balls. Arrange them about 2 inches apart on your prepared baking sheets. For an extra pretty touch, feel free to press a few extra mix-ins onto the top of each cookie before baking! Bake for 10-12 minutes (10 minutes for chewier centers, or 12 minutes for crispier edges).
Once baked, let the cookies cool on the baking sheets for 5 minutes. Then, carefully transfer them to a wire rack to cool completely for another 10 minutes. Enjoy your perfectly crafted holiday treats!