In a large mixing bowl, whisk to combine the flour, sugar, salt, and pepper. Fold in the cheese. Add the butter and smash it into the flour until the mixture is shaggy. Drizzle in 1/3 cup water and fold it into the flour mixture, adding more water as needed for the dough to hold together.

Turn the dough out and form it into a rough disc. Wrap in plastic wrap and chill for 30 minutes.

On a lightly floured surface, roll the dough into a 3/4-inch rectangle, fold it into quarters, re-wrap, and chill for another 30 minutes. Repeat this process 2 - 3 more times.

Prepare the zucchini by layering it on towels, sprinkling with sea salt, covering with more towels, and letting it sit for at least 30 minutes.

Preheat the oven to 425 degrees F. Line a 13 x 18-inch baking sheet with parchment paper.

Roll the dough into a 15 x 20-inch rectangle, place it in the baking sheet, and chill until ready to assemble the tart.

Heat a small skillet over medium heat, add the oil, shallots, and red pepper flakes. Cook until shallots are toasted, about 3 minutes. In a small bowl, combine this mixture with the Dijon.

Spread a thin layer of the shallot-Dijon mixture over the tart dough, leaving a 2-inch border. Sprinkle with all but 2 tablespoons of the cheese.

Layer the zucchini, finish with black pepper, and brush the dough border with egg wash. Fold and crimp the corners closed, finishing with more egg wash.

Bake for 20 minutes, then sprinkle the remaining cheese over the top and bake for another 10 - 15 minutes until the zucchini are golden and the crust is deep golden brown.

Set the tart aside to cool for 10 minutes, sprinkle with basil, slice, and serve.