Finely chop shallots, and garlic, then add into a pan on medium heat with olive oil and cook for about 2 minutes; stir in chopped bell peppers and continue to cook for about 5 minutes
While the aromatics are cooking, brown ground beef in a separate pan and drain when fully cooked. Pour ground beef into the pan with your aromatics.
Add in arborio rice, chicken broth, marinara, Italian seasoning and salt. Cover and reduce to a simmer. Cook until rice absorbs all the broth.
While the filling is cooking, cut bell peppers length-wise. and scoop out seeds and pith with a spoon. Preheat oven to 350 F.
When filling is done cooking, stir in mozzarella cheese. Scoop in the filling into each bell pepper and place on a sheet pan, or casserole dish. Top each stuffed bell pepper with a little more marinara and cheese. Cook for 20-25 minutes until cheese is melted and bell peppers are tender.