Melt butter or oil in a pot over medium heat, then add the rice. Toast the rice until it starts to color.
Add the broth and bring to a boil. Cover and lower the heat to maintain a low boil for 45 minutes. Check to see if the rice needs more liquid. If it does, add one cup at a time and continue cooking until the rice is soft.
While the rice boils, dice the vegetables into very small pieces.
Cook the sausage, onion, and carrots in a large frying pan. Brown the sausage meat, breaking it up as it cooks.
When the carrots begin to soften, add the zucchini or squash to the pan. Season with salt, pepper, and Italian seasonings.
Once the veggies are soft, add chopped spinach or kale (if using) and stir until it wilts, then remove from heat.
Cut each pepper in half and remove the seeds.
After the rice is done cooking, add the veggies to the rice and mix to combine.
Stuff each pepper with a heaping scoop of the rice mixture, dividing it evenly between the peppers.
Bake in a 400° F oven for 30 minutes. Then top with cheese (if using) and return to the oven until peppers are soft and the cheese begins to bubble (5-10 minutes).