Slice the fresh Creole tomatoes, reserving all juices released. Season with salt, black pepper, and cayenne pepper. Set aside.
Carefully roll out one Schar gluten free puff pastry sheet. Line a greased square cast iron skillet with the sheet. Use a fork to poke holes in the sheet. Then, score the 2-inch edge of the entire sheet with a sharp knife. (But do not cut all the way through.)
Bake for 15 to 20 minutes, or until golden brown.
Use a basting brush to spread the Creole mustard over the bottom of the warm gluten free puff pastry tart shell.
While the puff pastry bakes, caramelize the onion, bell pepper and celery in the butter or oil. When browned, add the garlic and cook for one additional minute. Remove from heat.
Chop the mozzarella into small cubes, then grate the Gouda into shreds.
Spoon about half of the caramelized vegetable mixture over the Creole mustard atop the puff pastry. Sprinkle about half of the cheeses over the veggies, then top with a layer of sliced tomatoes. Repeat the layers, topping the last tomato slice layer with a bit of both cheeses.
Bake for an additional 10 to 15 minutes, or until the tomatoes soften and the cheese melts.
Make a basil and parsley chiffonade by rolling the basil and parsley leaves tightly together, then slicing them horizontally into strips. Sprinkle the chopped herbs over the tart just before serving.