Lemon or Lime Tart -- Not for the Faint of Heart

I mean this literally: this tart is loaded with butter and eggs, so if your cholesterol is already high, beware! As an occasion indulgence it is well worth it. The crust is quick and easy to make, and it is crumbly but still holds its shape. The filling has a strong, smooth, and invigorating citrus flavor, with great texture. Active preparation time is only about 1 hour, and it can be made ahead of time with no last minute preparations, which makes it ideal for dinner parties.
Here are the ingredients for both the crust and filling:

2 sticks (16 tablespoons) unsalted butter
1/2 teaspoon vanilla extract
1/4 cup confectioners' sugar
1 pinch salt
1 1/4 cup unbleached all-purpose flour
2 large eggs at room temperature
3 large egg yolks at room temperature
1 cup regular (granulated) sugar
1/2 cup freshly squeezed lemon or lime juice (about 4 lemons or 5 limes)

Special equipment:
Double boiler
Pie pan with flat removable bottom (optional, but very handy for cutting and serving without breaking the crust)

Step 1: Pie Crust

Preheat oven to 350°F

Melt one stick (8 tablespoons) unsalted butter and let cool

Combine melted butter, 1/2 tsp vanilla extract, 1/4 cup confectioners' sugar and pinch of salt and blend with a spoon.

Gradually add flour till you form a smooth, soft dough with a consistency similar to cookie dough

Place in center of pan and press down with fingertips as evenly as possible on bottom and sides of the pan

Bake in the center of the oven for 12 to 15 minutes, till it's lightly browned. You do not need to prick or weigh this crust.

Step 2: Pie Fill

While the pie crust is baking,

Cut one stick of butter into 8 pieces.

Combine eggs, egg yolks and sugar in double boiler.

Place over simmering water. The top pan should be just above, not touching the simmering (not boiling) water.

Whisk, and watch the mixture transform. It will start bright yellow and grainy. As the sugar melts it become more liquid, paler, and frothy on top. After about 8 to 10 minutes it will thicken and become pale lemon colored.

Add butter, one piece at a time, letting each piece melt before adding the next.

Add the lemon or lime juice. When I use lime I also put in a bit of green food coloring, just so people eating the pie will know what flavor to expect. Continue whisking until the mixture is thick and custard-like and the first bubbles appear -- but do not let it boil. This will take about 3 or 4 minutes.

Step 3: Finish!

Pour the filling into the pre-baked pie crust, and smooth with a spatula.

Leave it to set for a minimum of 30 minutes. Although you can put it in the refrigerator (it will help it set) serve the tart at room temperature.