Preheat the oven to 400 degrees. Line a baking sheet with parchment paper. Spoon small mounds of 1/4 cup Parmesan onto the sheet and flatten them slightly. Bake for 5 to 7 minutes until golden and crisp, then set aside to cool.

Heat the olive oil in a large skillet over medium heat. Add the sausage and cook, breaking it up with a spoon, until browned and cooked through. Remove the sausage to a plate and leave the drippings in the pan.

Add the onion to the same skillet and cook for 3 to 4 minutes until softened. Stir in the garlic and cook for 1 minute more.

Add the Arborio rice and stir to coat it with the oil and drippings. Cook for 2 minutes until the edges look slightly translucent.

Pour in 1 cup of warm broth and stir until mostly absorbed. Continue adding broth 1/2 cup at a time, stirring often, until the rice is tender and creamy. This takes about 18 to 20 minutes.

Stir in the pumpkin puree, cooked sausage, remaining Parmesan, and butter. Season with salt and pepper. Cook for 2 more minutes until everything is heated through and well combined.

Serve the risotto in bowls and top each portion with a few Parmesan crisps.