1 Salt and drain the zucchini: Toss the grated zucchini with 1/2 teaspoon of salt and place in a colander to drain (in a sink or over a bowl). Let drain for 30 minutes to an hour.
After at least 30 minutes, use your (clean) hands to press and squeeze the grated zucchini against the colander to release more moisture.
Then use double layered sturdy paper towels or a clean tea towel to wrap up the zucchini and squeeze out even more moisture.
2 Whisk together the mayo and eggs, then whisk in the bread, green onions, garlic, zest, rosemary, cheeses, pepper: While the zucchini is draining in step 1, whisk together in a large bowl the mayonnaise and eggs until smooth.
Then add the bread, green onions, garlic, lemon zest, rosemary, grated cheddar, Parmesan, and black pepper. Let that sit while the zucchini is draining so that the bread breaks down in the mixture.
3 Prepare pans, preheat oven: Grease the wells of 2 mini-muffin tins with olive oil. Preheat the oven to 350°F.
4 Stir zucchini into batter, spoon into mini-muffin tins: Stir the drained, squeezed zucchini into the egg mixture until evenly distributed. Spoon the mixture into the wells of the mini-muffin tins, about a heaping tablespoon each.
5 Bake for 25 minutes at 350°F.
6 Cool and release zucchini bites from pan: Let cool for 5 minutes, then run a knife around the edges of the zucchini bites to loosen them from the pan. Remove from the pan to a rack to cool further.
Eat warm or cool to room temp, then chill or freeze to reheat later.