Preheat the oven to 350 degrees F. Line a baking sheet with parchment paper.

Mix the flour and baking soda in a small bowl.

In a large bowl, whisk the butter and sugars until they are combined. Add the egg, egg yolk, and vanilla and stir until mixed. Gradually add flour and mix until a dough forms – it will look crumbly at first, but it will come together. I even used my hands to help at one point. Stir in the white chocolate chunks - or you can add the chunks when you scoop the dough into balls.

Scoop the dough out in 1 to 2 tablespoon scoops. Roll into a ball and add more white chocolate inside if you wish. Place the nonpareils on a plate and roll the dough through the sprinkles, pressing gently to adhere.

Bake for 8 to 12 minutes or until the edges are slightly brown. The centers should be soft and puffy. Do not over bake. Let cool completely then dig in!

Note: to melt the butter I simply microwaved it, and to let it cool I allowed it to sit for about 10 minutes.