Make the crust: In a medium bowl, combine the graham cracker crumbs, sugar, melted butter, and vanilla extract. Stir until well mixed. Press the mixture into the bottom of mini tart pans or a muffin tin, making sure the crusts are even and well-formed. Bake at 350°F (175°C) for 8-10 minutes or until golden brown. Remove from the oven and set aside to cool.

1. Prepare the chocolate filling: In a heatproof bowl, melt the semisweet and unsweetened chocolate together. You can do this in the microwave, stirring every 20-30 seconds, or using a double boiler over low heat. Once melted, let the chocolate cool slightly. In a separate large bowl, beat the softened butter and powdered sugar together until smooth and fluffy, about 3 minutes. Add the melted chocolate to the butter-sugar mixture and beat until fully combined. Add the eggs, one at a time, beating well after each addition. Mix in the vanilla extract. Finally, add the heavy cream and beat the mixture until it becomes light, fluffy, and smooth, about 3 minutes.
2. Assemble the pies: Spoon the chocolate filling into the cooled crusts, filling them almost to the top. Smooth the tops with a spatula to make them even. Chill the mini pies in the refrigerator for at least 4 hours or overnight to allow the filling to set.
3. Make the whipped cream topping: In a chilled mixing bowl, whip the heavy cream and powdered sugar together until soft peaks form. Be careful not to overwhip, as it can turn into butter. Spoon or pipe the whipped cream onto the chilled pies just before serving.
4. Garnish: Garnish the pies with chocolate shavings or grated chocolate for an extra touch of elegance.
5. Serve: Serve the pies chilled for the best texture and flavor.