Preheat oven to 180°C (350°F).
In an ovenproof pot, melt 1 tablespoon (20g) butter over medium-high heat.
Add minced garlic and diced onion; cook until the onion turns translucent.
Stir in chopped sage and cook for 1 minute until fragrant.
Add arborio rice and stir until the grains are coated and semi-translucent.
Pour in white wine and cook until it fully evaporates, about 1 minute.
Add cubed pumpkin and broth, stir, and heat through (do not simmer).
Cover pot with a lid or foil and bake for 25 minutes, until rice is just tender (add 5 more minutes if needed).
Stir in remaining butter and parmesan, mixing vigorously until pumpkin becomes a creamy puree.
If the risotto is too thick, add a splash of hot water to achieve a loose, porridge-like consistency.
Serve immediately, topped with crispy sage, brown butter, and extra parmesan.