Preheat oven to 350º F. Put the flour, butter and salt into a food processor. Pulse about 30 times. Check the consistency of the dough. You want to see the butter in small pieces (the size of small peas or large grains of rice). When you have reached that consistency, dump the contents into a wide bowl.

Add 6 tablespoons of ice water to the bowl and with one hand, with fingers in a “claw” shape, mix the dough. Squeeze dough in your hands. If it holds together for a moment before crumbling, it’s ready. If it’s completely dry and does not hold together for a moment, add a tiny bit more water. Mix again with your hand. You do not want to add too much water.

Lay out some plastic wrap. Turn the contents out onto the plastic wrap (it’s desirable that it is not in one big ball, but still a bit crumbly) Pull up the sides of the plastic wrap, using it to help form a disc out of the pastry. Completely cover and chill in the refrigerator for 5 minutes.

Divide dough in quarters; save 2 quarters to make a different tart or increase the filling ingredients to make 4 tarts. Roll out each piece to 1/8-inch thickness. Dust the counter and dough with flour to prevent sticking.

Use a 9-inch plate as a guide and cut a circle around it. Crimp the edges of the tart, poke all over with the tines of a fork and lay out on a parchment-lined sheet pan. Brush the edges with the egg. Chill for 15 minutes.

Bake tarts in the middle of the oven for 15 to 20 minutes until nicely browned. Lift the tart carefully and make sure the bottom is cooked — it should be light brown. Let cool.

For Tart Filling

Mix the goat cheese with the milk and egg. Add the salt. Spread thinly onto tarts. Cook in a 300º F oven 5 to 7 minutes until the cheese firms up and appears dry on the surface. Cut tarts into 8 pieces.

Toss tomatoes with olive oil, season with salt and pepper and warm them in a low oven. Put pieces of tomato on tarts, cut-side up. Garnish with small basil leaves. Serve immediately.