In a food processor, place the butter, powdered sugar, lemon zest, and salt. Process until the mixture is thoroughly creamed together.

To the creamed mixture, add the egg yolks and vanilla. Process until combined.

Add in the flour and pulse until the mixture looks like coarse breadcrumbs. Try not to over mix.

Sprinkle the cold ice water over the flour and butter crumbs. Pulse just a few times to begin to combine. But do not process it into a ball. It should still be loose.

Turn the mixture onto a work surface and gather it into a ball, blending as you go to make a smooth dough. The key is not to overwork the dough, as it will become tough. Shape the dough into about a 2-inch-thick log shape, wrap in plastic wrap, and chill for at least 1 hour to relax.

Slice the dough into ¼ inch slices and press into an 11-inch tart pan with 1-inch sides and removable bottom. Press and smooth it out until you have a uniform smooth crust coming all the way up the side of the tart pan. Try not to have too thick of a bottom corner near the edge.

Prick a few places on the bottom of the crust with a fork.

Place the crust into the freezer and freeze for 1 hour, or even overnight.

To Make the Frangipane Filling and Finish the Tart

Preheat the oven to 350° for about 20-30 minutes.

When the oven has preheated, place the frozen tart shell directly from the freezer into the oven.

Bake for 15-20 minutes, or until the crust is beginning to become lightly golden brown.

Remove the baked tart shell from the oven and let cool for 20 minutes on a rack. Meanwhile, make the frangipane filling.

Turn the oven down to 325°

Pulse the blanched almonds in a food processor until you have fine ground almonds. Be careful not to just continually process, as the ground almonds will become almond butter if you process too far.

Transfer the ground almonds to a mixing bowl and set aside. There is no need to clean the bowl of the food processor.

In the bowl of your food processor, add the butter and the sugar. Process until light and creamy. You want to create a bit of an emulsion, so process it for a few minutes. Scraping the sides of the bowl as necessary.

Add in the eggs and vanilla. Process until smooth and the eggs have been fully incorporated.

Using a spatula, fold the butter mixture into the ground almonds. Add 1 cup of the chopped bittersweet chocolate. Continue to fold until the almonds and chocolate are thoroughly incorporated.

Let the frangipane chill for 10 minutes to firm up slightly.

Carefully spread the frangipane over the cooled tart crust.

Sprinkle the sliced almonds on top of the frangipane.

Bake the tart for 45 minutes, or until the tart is golden brown around the edges and is still slightly soft in the center.

Let the tart cool for an hour.

Finely chop the remaining ½ cup of chocolate.

Heat the 3 tablespoons of cream in the microwave or on the stovetop until very warm but not boiling.

Transfer to a small bowl or measuring cup and stir in the ½ cup chocolate. Continue to stir until the chocolate has melted.

Drizzle the chocolate across the top of the cooled tart.