Preheat the oven to 400ºF/200ºC. Line a baking tray with parchment paper.
Cut the zucchini into slices about 1/4-inch thick. Use a mandoline for even sizes. Shred the cheese if needed.
Arrange the slices on the baking tray, leaving about 1/2 inch (1 cm) between them. Add tomato paste to each slice and spread it slightly without reaching the edge. Sprinkle some cheese. If using other toppings, add them now.
Bake in the oven at 400ºF/200ºC for 10 minutes until the cheese is melty and bubbly. Serve warm!
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Notes
If you have leftovers, they can be stored covered in the refrigerator for 2-3 days. To reheat, place them back in the oven or under the broiler until warmed.Zucchini pizza bites can't be frozen; the zucchini gets watery and mushy when thawed.