Cut the zucchinis into 1-inch thick slices. Use a melon baller or teaspoon to scoop out the center of each zucchini slice, creating a small well for the filling.
Heat the olive oil in a skillet over medium heat. Add the chopped onion and minced garlic, and sauté until softened and fragrant, about 2-3 minutes
Chop the reserved zucchini flesh and add it to the skillet with the onions and garlic. Cook for an additional 3-4 minutes
Remove the skillet from heat and stir in the quartered cherry tomatoes, chopped roasted red peppers, sliced black olives, and crumbled feta cheese
Spoon the filling mixture into the wells of the zucchini slices, pressing down gently to pack the filling
Bake in the preheated oven for 15-20 minutes, or until the zucchini is tender and the filling is heated through
Serve these delicious Stuffed Zucchini Mini Bites as a flavorful appetizer or snack, and enjoy!