Preheat oven to 400 degrees.

In a large non stick skillet over medium high heat, cook the onions in the olive oil until the onions begin to turn translucent, about 5 minutes. Season with salt and pepper. Add in the ground turkey, and cook until cooked thru, about 8 minutes. Add in the rice, garlic, diced tomatoes, baby arugula, 1 cup mozzarella and 1/2 cup chicken stock. Stir to combine.

In an oven safe baking dish or skillet, add raw bell peppers and season with salt and pepper. Fill each bell pepper with the turkey and arugula mixture. Top the bell peppers with the remaining 1/2 mozzarella, and drizzle the tops with a small amount of olive oil.

Roast in the oven for 15-20 minutes, until the bell peppers start to become tender and the cheese is melted.