Rinse and dry the peppers. Slice the tops off of the peppers and remove the stems and seeds. Arrange the peppers in a 9x13 baking dish. Drizzle generously with olive oil. Roast 20 minutes.
While the peppers are roasting, make the filling: Heat 1 Tbsp. oil over medium heat in a large skillet. Saute the onion until slightly softened. Add the "beef" and saute 6-8 minutes, until browned. Remove from heat. Stir in the cooked rice and spices.
Remove the peppers from the oven. Stuff with the "beef" mixture. Place back into the oven for another 20 minutes. Sprinkle cheese over top and bake another 10 minutes. Garnish with cilantro, if desired.