Preheat your oven to 400℉
Unfold / unwrap your defrosted puff pastry sheet. Lay it on a lightly floured surface and roll it out to ⅛ inch thin.
Transfer the rolled out puff pastry to a large baking sheet lined with parchment paper. Using the tip of a sharp knife, score a 1 inch border around the edge.
In a medium bowl mix together the ricotta, lemon zest, parsley, salt, and black pepper.
Spread the ricotta herb mixture on the center of the puff pastry within the border.
Place the tomato slices in a single layer (a little overlap is okay to get good surface area), and spread the shallots around evenly.
In a small bowl whisk together the egg. Using a pastry brush, brush the egg wash around the border.
Bake the tart in a preheated oven for 18-20 minutes until deeply golden. Serve with fresh basil and grated parmesan cheese (optional).