Preheat oven to 375°F and line a baking sheet with parchment paper. 

1 Saute onion in olive oil over medium heat in a large saute pan, add optional mushrooms till golden and liquid has evaporated.  Add spinach, salt, and pepper to taste.  Remove from heat and set aside to cool.  2 In a medium bowl combine cornflake crumbs, garlic powder, onion powder, paprika, salt, and pepper.3 Evenly distribute filling among each of the cutlets.  Roll each cutlet up jelly-roll style and set on a plate seam side down. 4 Spread mayonnaise over each cutlet to coat it well.  Dip in crumb mixture.  5 Place cutlets on prepared baking tray and drizzle with olive oil.6 Bake uncovered for 35 minutes. Do not overbake.7 When cutlets are slightly cooled, slice into 3 or 4 pieces. Garnish with parsley.