Preheat your oven to 375F and grease a large baking dish lightly with olive oil spray. 

Slice the stem end off of each bell pepper and remove the seeds and membrane. If the peppers don’t sit upright, remove a small portion of the base (but make sure not to cut the bottom all of the way off– you want the pepper to hold the filling). Place the peppers cut side up in the pan. 

Bring a large pot of salted water to a boil over medium-high heat. Add the orzo and cook it for two minutes less than al dente. Once cooked, reserve ½ cup of the orzo cooking water and drain the orzo. Rinse the orzo with cold water to stop the cooking and set aside. 

Add the Italian sausage to a large skillet set over medium heat. Cook the sausage, breaking it up occasionally, for 7-8 minutes or until it is crisp and browned. Remove the sausage to a bowl with a slotted spoon. 

Add the onion to the pan and cook it, stirring occasionally, for 4-5 minutes or until it is soft and beginning to brown. If the pan becomes too dry at any point, add a tablespoon of olive oil. 

Once the onion is browned, add the garlic and cook for an additional minute. 

Next add the tomato paste, Italian seasoning, red pepper flakes, and dried fennel seeds. Stir until the tomato paste coats the onion. 

Add the reserved pasta water and stir. Deglaze the pan by scraping any browned bits from the bottom with a wooden spoon. 

Next add the diced tomatoes to the skillet, along with the orzo and Italian sausage. 

Remove from the heat and stir in 1 cup of mozzarella cheese. Taste and season with salt and pepper. 

Divide the filling between the peppers and top each pepper with additional mozzarella and grated parmesan. 

Bake for 25-30 minutes or until the peppers are tender and cheese is melted. Garnish with fresh basil and enjoy immediately. 

Store any leftover peppers in an airtight container in the fridge for up to three days.