Position a rack in the bottom of the oven, place an inverted baking sheet on top and preheat to 500 degrees .
In a small bowl, combine the olive oil, garlic and 2 pinches salt. Lightly flour a baking sheet, place 1 piece of pizza dough on top and stretch to fit the dimensions of the baking sheet. Drizzle 2 1/2 tablespoons garlic oil on top. Sprinkle half of the clams on top and season with 2 teaspoons parmesan, 1 1/2 teaspoons thyme and salt and pepper.
Set the baking sheet on the hot baking sheet in the oven. Bake until crisp and golden, about 20 minutes. Repeat with the remaining ingredients to make another pizza.