Place the saffron threads in a small cup with 2–3 tbsp of hot stock or water and let them infuse while you start the risotto.
In a wide saucepan, heat the butter and olive oil over medium heat. Add the finely chopped onion with a pinch of salt and cook gently until soft and translucent, about 5–7 minutes, without browning.
Add the rice and toast it, stirring continuously, for about 2 minutes until the grains look slightly translucent around the edges.Pour in the white wine and cook, stirring, until almost fully absorbed. Begin adding the hot veggie stock, one ladle at a time, stirring frequently. Wait until the liquid is mostly absorbed before adding the next ladle. Maintain a gentle simmer.
After about 10 minutes of cooking, stir in the saffron infusion (threads and liquid). Continue adding stock and stirring.
Cook until the rice is al dente and creamy, about 16–18 minutes total from the time you first added stock. When the rice is just done, remove the pan from the heat. Add the extra butter and grated Parmesan. Stir vigorously to “mantecare” (emulsify) the risotto, adding a spoonful of stock if needed so it flows slowly from a spoon (all’onda).