PREP THE VEGGIES: Preheat the oven to 425 degrees F. Chop the red onion into 1/2-inch pieces, slice the zucchini in half and then half again to get half-moons, half or quarter the mushrooms, depending on size (quarter large ones and halve smaller ones), and chop the red pepper into 1/2-inch pieces.
ADD TO SHEET PAN: Add all the cut veggies to a large (full-size; 26x18-inch) sheet pan or 2 half-sheet pans. Add the gnocchi to the pan. Drizzle the olive oil over everything and then add all of the seasonings: dried basil, dried oregano, dried parsley, garlic powder, onion powder, dried thyme, sweet paprika, red pepper flakes (if desired), and salt and pepper to taste (I add 1/2 teaspoon salt and 1/4 teaspoon pepper, but add to preference, noting that the Parmesan cheese also adds some saltiness). Toss until everything is well-coated and then spread everything into an even layer so no veggies/gnocchi are overlapping.
BAKE: Bake for 10 minutes; remove, flip and stir, making sure everything still remains in a single, even layer. Return to the oven for another 8-13 minutes or until veggies are cooked to desired preference (we like them around 10 minutes). Remove from the oven and grate Parmesan cheese right on top (I like using a microplane to get finely grated cheese); taste for any additional salt if needed. Serve hot. If desired, add spoonfuls of herb-y cilantro sauce on top (see notes).
Notes
We love this meal as is, but if you're someone that likes sauces, we've also tried it with a few spoonfuls of marinara and this cilantro sauce. To make the optional cilantro sauce, combine the following in a food processor and pulse until combined: 1 minced garlic clove, 1 tablespoon minced shallot, 1 cup (loosely packed) coarsely chopped cilantro leaves, 1 and 1/2 tablespoons red wine vinegar, 1 tablespoon lemon juice, 1/4 cup olive oil, 1/4 teaspoon red pepper flakes, and salt and pepper to taste (I use 1/2 teaspoon salt and 1/4 teaspoon pepper).