In a large mixing bowl, beat 1 cup of unsalted butter until creamy, about 2 minutes. Gradually add in 1 cup of granulated sugar, 1 teaspoon of baking powder, and ½ teaspoon of salt while mixing until light and fluffy. Beat in 1 large egg and 1 egg yolk, followed by 1 teaspoon of pure vanilla extract. Finally, gradually blend in 2 ½ cups of all-purpose flour until you have a soft dough that holds together.

Set aside ¾ cup of the prepared dough in a separate bowl. Add a few drops of peppermint oil and green food coloring to the reserved dough, mixing vigorously until the color is evenly distributed.

Roll the plain cookie dough into 25 equally sized balls, about 1 inch in diameter. Flatten each plain cookie ball slightly, press a mint ball into the center, and carefully wrap the plain dough around it to form a new ball.

Roll the stuffed cookie balls in a bowl of green nonpareil sprinkles, placing them on a parchment-lined baking sheet. Preheat your oven to 375°F and bake for 10-11 minutes.

Remove the cookies from the oven and let them cool on the baking sheet for about 5 minutes. Then, transfer the cookies to a wire rack to cool completely.