Preheat your oven to 350°F (175°C).
In a bowl, whisk together the flour, baking powder, and salt.
In another bowl, cream the butter, granulated sugar, and brown sugar together until light and fluffy.
Add the eggs one at a time, followed by the peppermint extract and the food coloring.
Gradually add the dry ingredients to the wet mixture, stirring until just combined.
Divide the dough in half and mix in the crushed peppermint candies to one half.
Add red food coloring to the other half of the dough if using.
Scoop tablespoons of each dough and create small balls side by side on a baking sheet.
Use a toothpick or skewer to swirl the two doughs together.
Bake for 10-12 minutes, or until the edges are lightly golden.
Allow the cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack.