Cut the ends off the zucchini, and then cut them in half lengthwise. Use a spoon to scoop the seeds out of the center of each zucchini half. A melon baller also works great to scoop out the insides. Brush the zucchini halves with avocado oil and lightly season them with salt and pepper, if desired.
Preheat a grill to high heat. If using an oven, preheat it to bake at 425º F. If using an air fryer, wait to top the zucchinis with pizza toppings before preheating it.
Grill the zucchini halves over high heat for 3-5 minutes to begin softening them. (skip this step if using an oven or an air fryer).
Add pizza sauce, shredded mozzarella cheese, and chosen pizza toppings to the center of each zucchini half. If desired, top them with scoops of ricotta cheese.
Put the zucchini pizza boats back on the grill for 5-10 minutes, until the cheese has melted and the toppings are hot. If baking these in an oven, add them to a baking tray and bake for 12-14 minutes. If using an air fryer, preheat it to 390º F for 5 minutes, and then add the zucchini pizza boats 2-3 at a time, and allow them to air fry for 8 minutes.
Garnish pizza boats with fresh basil, parmesan cheese, or Italian parsley, if desired.
After they have completely cooled, store leftover pizza zucchinis in an air tight container, and refrigerate for up to 4 days. Reheat these in the oven for 10 minutes at 425º F, or use an air fryer to reheat them at 390º F for 8 minutes. A small toaster oven would also be good.