In a bowl, combine spinach, cheese, garlic, onion, oil and mix.
Spread the mixture across the flank steak.
Roll up the steak from the bottom. Skewer the flank steak with toothpicks 2 inches apart. Slice flank steak into pinwheels.
Heat a cast iron on medium-high heat. Add 2 tbsp of olive oil to the pan and cook the pinwheels for 10 minutes per a side for med-well, longer for well done.
Remove steaks from skillet and toothpicks, then enjoy!
