Simplest Stuffed Peppers

1 lb. ground beef, preferably grass-fed, or dark meat ground turkey
2 tablespoons olive oil
1 cup diced onion
2 cloves garlic, minced
3/4 cup marinara sauce
1 tsp. salt
1/4 tsp. crushed red pepper flakes
1 tsp. oregano
4 cups baby spinach OR 3 cups chopped kale
1 1/2 cups shredded mozzarella cheese
3 large bell peppers, cut in half lengthwise, ribs and seeds removed

Preheat oven to 400 degrees.  If preparing the peppers to eat right away, set the pepper halves cut sides down in a 13×9 baking dish and roast at 400 degrees for 15-20 minutes, just until slightly softened.  If making the peppers in advance for a meal later in the week, skip this step and just place the raw pepper halves cut sides up in the baking dish.

In a large skillet over medium-high heat, saute the meat, onion, and garlic in the olive oil until the meat is browned and the onions are soft and translucent.  Add the marinara sauce and salt, pepper flakes, and oregano.  Stir to combine and simmer for 4-5 minutes.  Add the greens; cover and cook for an additional 5 minutes, until the greens are wilted.

Spoon the filling evenly into the pepper halves.  Top each pepper half with 3-4 tablespoons mozzarella cheese.  Cover the pan tightly with foil and bake at 400 degrees; if you’ve par-cooked the peppers, the baking time is 20-25 minutes, until the peppers are soft but still hold their shape.  If you’re assembling the dish to cook later, the baking time will be 40-45