Zest both lemons with a microplane and set the zest aside. Juice one lemon and set the juice aside too, you'll need about 3 tbsp.

Pour the stock into a 20 cm / 8-inch saucepan and bring it to a bare simmer over medium heat, about 95 C / 200 F. Keep it at that gentle simmer, not a rolling boil, for the whole cooking time.

Heat the olive oil and 30 g of the butter in a 28 cm / 11-inch heavy-bottomed pot over medium heat. Add the shallot and cook for 3 to 4 minutes, stirring, until soft and translucent but not browned.

Add the rice and stir constantly for 2 minutes, until the edges of the grains turn translucent and the centers stay opaque white. This tostatura step is what helps the rice hold its shape later.

Pour in the wine and stir until it's fully absorbed, about 1 to 2 minutes.

Add the warm stock one ladle at a time, stirring often, waiting until each addition is mostly absorbed before adding the next. This takes 18 to 20 minutes total.

Start tasting the rice around the 16-minute mark. It's done when the grains are tender with a slight bite left in the center, not chalky and not mushy.

Remove the pot from the heat. Stir in the remaining 40 g butter, the parmesan, lemon zest, and lemon juice, beating fairly hard for 30 seconds until the risotto turns glossy and pools into a slow wave when you tilt the pot. This is the mantecatura.

Season with salt and black pepper to taste. Cover and let it rest for 1 to 2 minutes off the heat, then spoon it onto warm plates immediately.