Preheat oven to 425 degrees. Tarts will bake for 15-20 minutes

Lay puff pastry flat on cutting board. On another clean cutting board, slice tomatoes and find a drinking glass that has the same circumference as the tomato. Use the opening of the glass to cut circular shapes out of the dough. Place parchment paper on baking sheet and line dough onto sheets. 

In a small bowl, scramble egg and add 1 tbsp of water to make the egg wash

Turn pan to medium heat and add butter

Add minced shallots and let cook for 3-4 minutes and add some salt and pepper

Add minced garlic, Italian Seasoning and stir until all ingredients are incorporated and softened. About 1-2 minutes minute

Turn off the heat and let sit until ready to assemble tarts

Brush a little egg wash onto each tart round and then add about 1 Tablespoon of onion and garlic mixture

On top of shallot mixture, add a sprinkle of gruyere cheese to each tart

Place slice of tomato on the very top and add salt and pepper and place in oven to cook at 425 degrees for 15-20 minutes