Preheat the oven to 350°F (175°C). Lightly spray a muffin-top pan with non-stick cooking spray and set aside.
In the bowl of a stand mixer, cream 1/2 cup softened butter and 1 cup vanilla sugar until light and fluffy, about 2–3 minutes.
Add 1 egg and 1 teaspoon vanilla to the butter mixture and mix until incorporated, scraping down the sides of the bowl as needed.
In a separate bowl, whisk together 1 cup all-purpose flour, 1/3 cup cocoa, 1/2 teaspoon baking soda, and 1/4 teaspoon salt.
Add the dry ingredients to the wet mixture and stir just until combined; do not overmix.
Fold in 1/2 cup heaping chopped Candy Cane Kisses and 2 ounces semi-sweet dark chocolate chunks by hand.
Spoon about 1/4 cup batter into each cavity of the prepared muffin-top pan and flatten each portion lightly; take care not to overfill.
Bake for 13 minutes, or until the edges are set and the centers look matte but are still slightly soft.
Cool the cookies in the pan for 5–10 minutes, then remove them to cool completely.
Serve warm or at room temperature.