Mix Taleggio, Parmesan, mayonnaise, chopped thyme, remaining 1/2 tsp salt, remaining 1/4 tsp pepper, and reserved chopped garlic and bits in a medium bowl. Gently dollop half of cheese mixture over bottom of crust, then spread into an even layer with an offset spatula (don't press too hard or you will break the crust). Layer half of tomato slices over and press down to even out layers. Repeat with remaining cheese mixture and tomatoes. Brush remaining garlic butter over tomatoes. Top with shallot and thyme leaves.