Creating Double Chocolate Peppermint Cookies is simple when you follow these steps:

1. Preheat the Oven: Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
2. Cream the Butter and Sugars: In a large bowl, cream together the softened butter, granulated sugar, and brown sugar until light and fluffy.
3. Add Eggs and Vanilla: Beat in the eggs, one at a time, followed by the vanilla extract until well combined.
4. Mix Dry Ingredients: In a separate bowl, sift together the flour, cocoa powder, baking soda, and salt.
5. Combine Mixtures: Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
6. Add Chocolate Chips: Fold in the semi-sweet chocolate chips and white chocolate chips (if using) until evenly distributed.
7. Add Peppermint Extract: Stir in the peppermint extract for that refreshing flavor.
8. Scoop the Dough: Using a cookie scoop or tablespoon, drop the dough onto the prepared baking sheet, spacing them about 2 inches apart.
9. Bake: Bake in the preheated oven for 10-12 minutes, or until the edges are set but the centers are still soft.
10. Cool: Remove from the oven and let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.
11. Top with Crushed Peppermint: If desired, sprinkle crushed peppermint candies on top of the cookies while they are still warm.

These steps will guide you in creating delicious Double Chocolate Peppermint Cookies that your friends and family will love.