1. Make the Tart Shells:

1. Preheat oven to 350°F (175°C). Grease a mini muffin tin or mini tart molds.
2. In a bowl, whisk together flour, powdered sugar, and salt.
3. Cut in the cold butter using a pastry cutter or fork until the mixture looks like coarse crumbs.
4. Add the egg yolk and mix until the dough begins to come together. If too dry, add 1 tbsp cold water.
5. Divide the dough into 12 equal portions and press into the mini tart molds, making sure the dough is even.
6. Prick the bottoms with a fork and bake for 12-15 minutes, or until golden brown.
7. Let cool completely before adding the filling.

2. Make the Chocolate Ganache Filling:

1. Heat the heavy cream in a small saucepan over medium heat until it just starts to simmer (don’t boil).
2. Pour the hot cream over the chopped chocolate and let sit for 2 minutes.
3. Stir gently until the chocolate is fully melted and smooth.
4. Add butter and vanilla extract, mixing until glossy.

3. Assemble & Chill:

1. Spoon or pipe the ganache into the cooled tart shells.
2. Let set at room temperature for 30 minutes, or refrigerate for 1 hour for a firmer texture.

4. Garnish & Serve:

1. Top with whipped cream, berries, nuts, or sea salt if desired.
2. Serve and enjoy!