1. 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.
2. Bake in a 325° oven until crust is pale gold, about 30 minutes (about 25 minutes in a convection oven).
3. 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.
4. 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.
5. 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.
6. 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.