Place the chicken leg quarters in a large pot, and fill with enough water to cover by 1 inch. Bring to the boil, then reduce heat to medium-low, cover, and simmer 40 minutes. Remove the legs and allow to cool. Strain and return the cooking liquid to the pot. Once the legs have cooled, remove and discard the skin and bones; chop the meat, and set aside.
Stir the brown rice into the reserved chicken stock and bring to the boil. Reduce heat to medium-low, cover, and simmer until the rice is tender, 45 to 50 minutes. Drain off any excess liquid, and add the rice to the bowl with the chicken.
Heat a large skillet over medium-high heat, and add the beef. Cook and stir until the beef is crumbly and no longer pink, about 7 minutes. Pour off any excess grease, and place the beef into the bowl. Stir in the oats, spinach, broccoli, kidney beans, carrots, garlic (if using), cottage cheese, and olive oil. Store the dog food in resealable containers in the freezer. Thaw the daily portions overnight in the fridge.