Notes: Up to 1 day ahead, bake crust, cool, wrap airtight, and keep at room temperature.
How to Make It
In a food processor or bowl, combine flour and butter. Whirl or rub with your fingers until fine crumbs form. Add egg and whirl or stir with a fork until dough holds together. Pat dough into a ball, then press evenly over bottom and sides of a 10-inch tart pan with removable rim.
Bake in a 325° oven until crust is pale gold, about 30 minutes (about 25 minutes in a convection oven).
Meanwhile, cut tomatoes in half and gently squeeze out seeds. Cut tomatoes crosswise into 1-inch-thick slices, and lay on towels to drain. Save ends.
Remove baked crust from oven and turn oven to 400°. Spread mustard over bottom of crust, then sprinkle evenly with 1 1/2 cups cheese. Fit largest tomato slices snugly in a single layer on cheese. Cut remaining tomato slices into pieces to fill the gaps; reserve extra tomato pieces for other uses.
In a small bowl, mix oil to blend with tomato paste, shallots, garlic, thyme, marjoram, and oregano. Spread over tomatoes. Sprinkle with remaining cheese. Arrange anchovies and olives on tomatoes.
Bake in a 400° oven until cheese is lightly browned, about 25 minutes (about 18 minutes in a convection oven). Remove pan rim. Cut the tart into wedges and serve hot or warm. Add salt and pepper to taste.