Heat the oven to 200 C / 400 F. Toss pumpkin cubes with 1 tbsp olive oil, salt, and pepper on a sheet pan 33 x 23 cm / 13 x 9 inch. Roast 25 to 28 minutes, flipping once, until edges caramelize and pumpkin is fork-tender.

Once cool enough to handle, mash about two-thirds of the pumpkin with a fork until mostly smooth. Leave the rest in small chunks for texture.

Warm the vegetable stock in a 2-quart saucepan over low heat and keep it at a bare simmer while you cook the risotto.

Heat 1 tbsp olive oil and 1 tbsp butter in a 12-inch / 30 cm sauté pan over medium heat. Add shallot and cook 3 to 4 minutes until soft and translucent. Add garlic and cook 30 seconds until fragrant.

Add arborio rice and stir to coat every grain in fat. Toast 1 to 2 minutes until the edges of the grains turn slightly translucent.

Pour in the white wine and stir until fully absorbed, about 1 minute.

Add warm stock one ladle, about 120 ml, at a time, stirring frequently and waiting until each addition is mostly absorbed before adding the next. This takes 20 to 25 minutes total.

Stir in the mashed pumpkin and pumpkin chunks during the last 5 minutes of cooking. Taste the rice for doneness, it should have a slight bite at the center, not a hard chalky core.

Off heat, stir in the remaining 1 tbsp butter and grated parmesan. Season with salt and pepper. If the risotto looks too thick, loosen with a splash of hot stock, it should fall from the spoon in a slow ribbon.

Melt 3 tbsp butter in an 8-inch / 20 cm skillet over medium heat until foaming. Add sage leaves in two batches of 8, frying 15 to 20 seconds per side until crisp and darkened at the edges but not black, they burn fast once the butter browns. Transfer to a paper towel and sprinkle with salt immediately.

Divide risotto among bowls, top with crispy sage leaves and toasted pumpkin seeds if using. Serve right away while the sage is still crisp.