From http://hostthetoast.com/, found via Reddit. Looks good...
Ingredients
½ cup seasoned breadcrumbs
¾ cup milk, divided
1 pound raw Italian chicken sausage, casings removed
1 (10 ounce) box frozen spinach, thawed and drained
1 large egg
¼ cup grated parmesan cheese
1 cup shredded mozzarella cheese, divided
Kosher salt and black pepper
4 large cubanelle peppers
¼ cup extra-virgin olive oil
1 cup marinara sauce
½ cup low-sodium chicken broth
1 cup Italian basil leaves, divided
Rice to serve, optional
Instructions
In a medium-sized bowl, mix the breadcrumbs with ¼ cup milk to form a thick paste. Mix in the chicken sausage meat, thawed spinach, egg, parmesan cheese, ½ cup of the mozzarella cheese, salt, and pepper. Set aside.
Use a pairing knife to cut around the stems of the peppers, then pull out the stems and discard them. Make a slit down the length of one side of the pepper, from the hole at the top to the tip. Pull out the seeds and guts through the slits and discard them.
Stuff the peppers with the chicken sausage mixture, making sure to press the stuffing in well. Set aside.
Heat the oil in a large skillet over medium-high heat. Once warmed, place the peppers in the skillet, open side down. Cook until the exposed stuffing is browned, about 5 minutes. Flip and lightly brown the bottoms, about 3-4 minutes. Pour in the marinara sauce and chicken broth, cover, and reduce to a light simmer. Cook until the filling is cooked through completely, about 25 minutes.
Uncover the skillet and add in the basil and the remaining milk. Stir well to combine and cook until warmed and the basil is wilted, about 5 minutes. Top with the remaining basil leaves and serve with rice, if desired.