Preheat the oven to 375 degrees Fahrenheit. If using a non-stick madeleine pan, spray with cooking/baking spray. If not using non-stick, brush with melted butter and then coat each cavity with flour or cocoa powder and shake off excess.
In a medium bowl, sift together flour, cocoa powder, baking powder and salt. Set aside
In a stand mixer with the whisk attachment or medium bowl and hand mixer, beat eggs and sugar on medium high for about 5-8 minutes. They should be light yellow and form ribbons when lifting the batter up.
Beat in the vanilla extract and peppermint extract until combined.
Add the dry ingredients and beat on low until just combined, with some streaks of flour still visible.
Slowly pour in the melted and cooled butter and mix on low until fully incorporated.
Use a piping bag or ziptop bag with the corner cut off to pipe each madeleine cavity about ¾ full of batter.
Chill the filled pan(s) for about an hour in the refrigerator.
Bake about 7-10 minutes until puffy and the lightly springing back when touched. Cool in the pan for a few minutes before transferring to a wire rack to cool completely.
Once cooled, melt the chopped chocolate in the microwave in 30 seconds intervals, stirring after each interval, until it’s fully melted.
Dip the end of each madeleine into the melted chocolate and then sprinkle with crushed peppermints.
Allow to cool on a wire rack and then store in an airtight container for up to 2 days.