Preheat your oven to 350°F (180°C). Line baking sheets with parchment paper for easy cleanup.
In a medium bowl, gently whisk together the flour, baking soda, baking powder, and salt. Set this aside.
In a large mixing bowl, beat the softened butter with both the granulated and brown sugars until the mixture becomes light and fluffy. This step is key for a soft texture!
Beat in the egg until it's fully combined, then stir in both the pure vanilla extract and refreshing peppermint extract. Mix well.
Gradually add the dry flour mixture to the wet ingredients. Mix just until everything comes together into a thick, non-sticky dough. Remember, less mixing means more tender cookies!
Gently fold in the white chocolate chips and crunchy peppermint pieces using a spatula until they are evenly distributed throughout the dough.
Scoop out about 1 1/2 tablespoon portions of dough and roll them into neat balls. Place them onto your prepared baking sheets, leaving some space between each. Bake for 7-9 minutes, just until the edges are lightly golden and the centers look set but still wonderfully soft.
Remove the cookies from the oven and let them cool on the baking sheets for 4-5 minutes. This helps them firm up before you transfer them to a wire rack to cool completely.