Preheat the oven to 350° F. Generously grease a mini muffin pan.
Melt the butter in a microwave-safe bowl for 30-45 seconds. Combine with the brown and granulated sugar and beat on medium speed until well combined. Next add the eggs and vanilla extract and continue beating until well incorporated.
In a separate bowl, combine the remaining dry ingredients, stir to combine and slowly add into the dough, mixing on low speed until dough comes together.
Use a medium cookie scoop (approximately 1-1.5 tablespoons) to scoop dough into prepared pan. Bake at 350°F for 10-12 minutes. Allow to cool for at least 5 minutes. Use a tart shaper to gently push down the middle of the cookies and cool completely in the pan.
For the filling: Combine chocolate and heavy whipping cream in a microwave-safe bowl. Microwave at 50% power for 1-2 minutes, stirring occasionally until it’s completely melted, then stir until smooth.
Use a spoon to fill the center of each cookie with ganache. Garnish with sprinkles or chopped peppermint candies if desired. Allow ganache to set completely prior to packaging, refrigerate if necessary. Note: Store in an airtight container at room temperature or you can make these ahead and store in the freezer until you’re ready to share!