Rinse the spinach well in cold water to make sure it's very clean.

In a very large skillet or pot, heat the olive oil and sauté the garlic over medium heat for about 1 minute.

Add all the spinach, the salt, and pepper to the pot, toss it with the garlic and oil, and cook it for 2-3 minutes or until dark green but not soggy. Make sure the butter and oil fully coat the veggies.