Start by preheating your oven to 350°F and preparing your baking sheets with parchment paper. While the oven heats, chop your peppermint bark into small pieces—about 1/2-inch chunks work best. Separate this into two portions: 1.5 cups for mixing into the dough and 0.5 cups for topping after baking. This preparation ensures everything is ready when you need it and prevents the peppermint bark from melting during prep work.

In a medium bowl, whisk together the flour, baking powder, baking soda, and sea salt. Whisking instead of simply mixing incorporates air into the dry ingredients and ensures the leavening agents are evenly distributed throughout, which gives you more consistent rise and texture in your final cookies.

In a large mixing bowl, beat the softened butter, light brown sugar, and granulated sugar together for about 2-3 minutes until the mixture is light, fluffy, and pale. This creaming process incorporates air into the butter, which helps create a tender cookie with good structure. I like using both brown and granulated sugar together because the brown sugar adds moisture and chewiness while the granulated sugar helps with spread and crispness at the edges.

Add the room temperature eggs one at a time to your creamed butter mixture, beating well after each addition. Then add the vanilla extract and mix until fully combined. Room temperature eggs blend more smoothly into the butter mixture, creating a more homogeneous dough and helping everything emulsify properly for better cookie texture.

Add the dry ingredient mixture from Step 2 to your wet ingredients and mix on low speed until just combined—don't overmix, as this can lead to tough cookies. Once the dry ingredients are incorporated, fold in the 1.5 cups of chopped peppermint bark and the semi-sweet chocolate chips using a spatula or wooden spoon. I prefer folding by hand at this point because it prevents overworking the dough and helps keep the peppermint bark chunks intact rather than breaking them apart.

Scoop the dough into balls using a cookie scoop or tablespoon and place them about 2 inches apart on your prepared baking sheets. Sprinkle each cookie lightly with flaked sea salt—this enhances the sweetness of the peppermint and chocolate while adding a sophisticated contrast. Bake for 10-12 minutes until the edges are golden brown but the centers still look slightly underdone. The cookies will continue to cook on the hot pan after removal from the oven.

Remove the cookies from the oven and let them cool on the baking sheet for 2-3 minutes until they're just set but still warm. Working quickly while the cookies are warm, press about 1 tablespoon of the reserved 0.5 cup chopped peppermint bark on top of each cookie—the warmth will slightly soften the bark, helping it adhere to the cookie. Once the bark is applied, let the cookies cool on the sheet for another 5 minutes, then transfer them to a wire rack to cool completely. This two-stage cooling prevents the warm cookies from breaking when moved.