In the bowl of a large food processor, place flour and powdered sugar. Pulse briefly to blend. Scatter butter cubes evenly over top of flour and powdered sugar mixture. Pulse to cut in butter until no lumps are visible and mixture resembles the texture of cornmeal. Add egg yolks and pulse to blend, mixing only until comes together (about a minute). Avoid overprocessing.

Using your fingers, pat dough into a 10-inch tart pan with a removable fluted rim. Chill shell for 30 minutes. Note that you may have leftover dough.

Place chocolate in a microwave-safe bowl and heat in 30 second intervals on medium in a microwave. Stir between intervals until melted, about 3 to 4 minutes. Spread melted chocolate on the bottom of the shell and chill the shell for an additional 15 minutes.

Preheat oven to 350°F.

In a heavy saucepan combine brown sugar and corn syrup, bring the mixture to a boil, stirring, and simmer it for 5 minutes.

Let the mixture cool until it is no longer bubbling, add butter, and stir mixture until the butter is melted.

In a bowl whisk together eggs, vanilla and a pinch of sea salt. Add syrup mixture in a slow stream, whisking.

Add pecans evenly to shell, pour in egg mixture and tap down pecans to coat them with the egg mixture.

Bake the tart in middle oven for 40 to 45 minutes or until the crust is pale golden.

Transfer to a wire rack to cool.

Serve at room temperature with freshly whipped cream or vanilla ice cream.

Keeps at room temperature for 2 days.