Vegetable Stuffed Portabella Mushrooms

large portabella mushrooms, wiped with a damp paper towel

olive oil, plus more for coating the mushrooms

large sweet onion, diced

medium zucchini, diced

roasted red pepper, diced

– 6 sun dried tomatoes, chopped

– 3 cloves garlic, minced

large handful of spinach

dried oregano, crushed between your fingers

crushed red pepper flakes

freshly ground black pepper,

dried breadcrumbs (see notes to make this gluten free)

grated Parmesan (see notes to make this vegetarian/vegan)

shredded mozzarella cheese (see notes to make this vegan)