In a large bowl, whisk together the flour, cocoa powder, powdered sugar, and salt.
2. Step
In a medium bowl, whisk together the egg yolk and heavy cream.
3. Step
Add the butter to the flour mixture and toss to coat, then pour in the egg yolk mixture. Use a pastry cutter to cut the butter into smaller pieces, then continue mixing with your hands until the dough comes together in a ball. Wrap the dough in plastic wrap and refrigerate for 1 hour.
4. Step
Preheat the oven to 350°F (180°C).
5. Step
Place the dough between 2 sheets of parchment paper, then roll out into a 12-inch circle, returning to the refrigerator if the dough begins to soften too much. Peel off one layer of parchment, then carefully flip the dough into a 10-inch tart pan. Remove the top layer of parchment and gently press the dough flush against the fluted edges of the pan, then trim the excess dough around the rim. Use a fork to poke holes all over the bottom of the tart shell, then chill for 10-15 minutes. Replace the parchment paper on top of the tart and fill completely with pie weights, dried beans, or coffee beans.
6. Step
Bake for 25–30 minutes or until the tart shell is puffy and baked through. Let cool completely before filling, about 20 minutes.
7. Step
Make the mint cream: In a medium, microwave-safe bowl, combine the white chocolate chips, heavy cream, and butter. Microwave in 30-second intervals, stirring between, until melted and smooth. Add the peppermint extract and food coloring and stir until evenly incorporated.
8. Step
Pour the mint cream into the tart shell and spread in an even layer. Chill in the refrigerator for 20 minutes, or until the filling is solid.
9. Step
Make the chocolate ganache: In a medium, microwave-safe bowl, combine the dark chocolate, heavy cream and peppermint extract. Microwave in 30-second intervals, stirring between, until smooth.
10. Step
Pour the ganache over the mint filling and spread into a smooth, even layer. Grate 2 Andes chocolate mints over the top of the ganache, then place the remaining whole Andes mint in the center. Chill the tart for 20 minutes, or until the ganache is solid.
11. Step
Keep refrigerated until ready to slice and serve, up to 2 days.
