Add chickpeas to the food processor and pulse until coarsely chopped. Add lentils, mushrooms, black beans and oatmeal. Pulse until a pliable mixture. Remove from processor to large bowl.
To the mixture add grated beets, nutritional yeast, arrowroot starch chopped parsley, rosemary, salt, pepper, and cayenne/chili flakes. Mix well with hands.
Form patties then refrigerate for 30 minutes before cooking.
Heat oven to 450°F. In ovenproof skillet, over medium-high heat and a little oil cook patties 3 minutes per side.
Place burger patties in the oven for 10 minutes. Dress burgers as desired.