For the crust:

1. Put the flour, sugar, and salt in a food processor, pulse to blend. Scatter in the butter, and pulse about a dozen times, until the butter is cut in. You’ll have pieces the size of oatmeal flakes and others the size of peas.
2. Stir the yolk to break it up and add it in 3 additions, pulsing after each.
3. Pulse until the dough has curds and clumps; it should hold together when you pinch it. Turn it out onto a counter, knead it into a ball and flatten it into a disk. Wrap in plastic wrap and chill.
4. Roll the dough into an 11-inch circle between layers of parchment or wax paper. If you do not have either on hand, roll out onto a floured work surface.
5. Fit the dough into a 9-to-9½-inch tart pan with a removable bottom, trimming the top evenly with the pan’s edges. Refrigerate the crust in the pan for at least 1 hour. If you need it in a hurry, you can put it in the freezer until firm.
6. Heat the oven to 400. Place the pan on a baking sheet, and cover with a piece of buttered foil or parchment, pressing it lightly to cover the crust’s bottom and sides; fill with rice or dried beans. This will help the tart hold its shape.
7. Bake for 20 minutes. Remove the foil and rice. If you’re going to bake the tart again with a filling, bake it uncovered for 5 minutes more. If you’ll be using a no-bake filling, bake the uncovered crust for an additional 8 to 10 minutes.
8. Cool for at least 30 minutes before filling.

For the filling:

1. Heat heavy cream and milk over medium until it simmers around the edges. Remove from heat. Add chocolate and stir until smooth. Whisk in sugar and salt. Beat eggs in a small bowl and add into the chocolate mixture until smooth.
2. Pour filling into cooled tart shells and bake at 325 degrees for 15 to 20 minutes until the surface is glossy.

For the ganache:

1. Heat heavy cream over medium heat until it simmers around the edges. Do not overheat the heavy cream.
2. Measure chocolate chips in a large mixing bowl.
3. Once heavy cream is ready pour over chocolate chips, let sit for a minute. Whisk until completely combined.