Add rice and chicken broth to a small saucepan then bring to a simmer. Place a lid on top then turn heat down to low and simmer for 10 minutes. Remove pan from heat then let sit with the lid on for 5 minutes. Fluff with a fork then set aside.
Meanwhile, brown sausage in a large, 12” skillet over heat that’s just a touch above medium. Once cooked, remove sausage to a plate then set aside.
Add a drizzle of extra virgin olive oil to the skillet then add bell pepper and shallot or onion, season with seasoned salt, and then saute until vegetables begin to soften, 5 minutes. Turn heat up slightly then add zucchini and sweet corn, season with more seasoned salt, then continue to saute until all the vegetables are tender, 5-6 more minutes. Add garlic then saute for 1 more minute. Turn the heat down slightly and/or add more extra virgin olive oil at any point. Taste vegetables then add more seasoned salt if necessary, and then set aside.
Add flour to a small saucepan then whisk while cooking for 1 minute. Slowly stream in milk while whisking to avoid lumps. Turn heat to medium then continue to whisk slowly but constantly until milk is thickened and bubbly, 1-2 minutes. Remove pan from heat then add 3/4 of the shredded cheese and stir until smooth. Taste and add salt if necessary.
Add cooked rice, sausage, and cheese sauce to the skillet with the vegetables then mix until well combined. Scoop mixture into a nonstick-sprayed 9x13” baking dish then top with remaining shredded cheese and broil until top is golden brown. Sprinkle with fresh basil, if using, then scoop onto plates and serve.