Start by preheating your oven to 350 degrees F. This step is crucial as it ensures an even bake right from the beginning. If the oven isn’t hot enough, your cookies may spread too much.
Next, line a baking sheet with parchment paper. This prevents the cookies from sticking and helps them bake evenly. I usually prepare two sheets so I can bake multiple batches without delay.
In a small bowl, mix together the all-purpose flour and baking soda. This step ensures that the leavening agent is evenly distributed throughout the flour.
In a large mixing bowl, whisk the unsalted butter and both types of sugar until they are combined and creamy. You want the mixture to be light in color and fluffy, which will take about 2 to 3 minutes.
Add the whole egg, egg yolk, and vanilla extract to the butter and sugar mixture. Stir until everything is well incorporated. The dough should be smooth and a bit thick.
Gradually add the flour mixture to the wet ingredients, mixing until a dough forms. It may appear crumbly at first, but don’t worry! Keep stirring, and it will come together beautifully. Sometimes I find using my hands helps.
Gently fold in the chopped white chocolate until evenly distributed. You can also reserve some for pressing into the tops of the cookies later.
Scoop out tablespoon-sized portions of dough and roll them into balls. If you want, you can add extra white chocolate pieces inside each ball for a gooey surprise.
Next, pour the nonpareil sprinkles onto a plate. Roll each dough ball in the sprinkles, pressing gently to make sure they stick.
Place the cookie balls onto the prepared baking sheets, leaving enough space between each for spreading. Bake for 8 to 12 minutes or until the edges are slightly brown. The centers should be soft and puffy—don’t overbake!
Once baked, allow the cookies to cool on the baking sheet for about 5 minutes before transferring them to a wire rack to cool completely. This waiting period helps them set properly.
Finally, dig in! Enjoy your delicious Chewy Sprinkle Cookies with a glass of milk or your favorite beverage.