Preheat the oven to 350 F. Line a 12 cup muffin pan with paper liners. In a large bowl, whisk together flour, sugar, cocoa powder, salt, and baking soda.
Add in eggs, melted butter, and peppermint extract, mix until smooth. Evenly divide the brownie batter between the lined muffin cups. Bake for 15-20 minutes.
Remove from the oven, and place one unwrapped chocolate kiss on each brownie cup.