Preheat the oven to 392°F/200°C.
Cut the zucchini to round pieces and add salt. Remove the excess water.
Roast the pieces of zucchini on hot olive oil for about 2 minutes on each side.
In meantime, cut the rest of the ingredients into desirable shapes. Shred the cheese and set aside.
Cut the puff pastry sheet to 6 pieces. Place them on the baking sheet, covered with parchment paper. Top the pieces with olive oil using a brush.
Add the shredded cheese on the puff pastry pieces top it with mozzarella pieces. Save 1/4 of mozzarella for the finish.
For zuccini pizza tarts add roasted zuccini pieces and garlic mixed with some olive oil on top.
For tuna tarts, top the pastry and cheese with sliced pieces of onion, bell pepper and tuna pieces from the can.
For a Margherita version of puff pastry pizza tarts, add, sliced tomato, bell pepper, olives and and a pinch of origano.
Sprinkle with a pinch of salt and black pepper and the leftover of shredded mozzarella cheese.
Bake at 425F/200C for about minutes.
Enjoy your puff pastry pizza tarts.