Snap off the woody ends of the asparagus and add those trimmings to a saucepan with the vegetable stock. Bring to a bare simmer over low heat and keep the stock hot.
Cut the remaining asparagus stalks into 0.5-inch pieces and reserve the tips separately.
In a wide heavy pot, heat the olive oil and 1 tbsp of the butter over medium heat. Add the chopped onion and cook, stirring, until translucent but not browned, 4β5 minutes.
Stir in the rice and toast, stirring constantly, until the grains are hot and edges look translucent, about 2 minutes.
Pour in the white wine and cook, stirring, until almost completely evaporated, 1β2 minutes.
Begin adding the hot asparagus-infused stock a ladleful at a time, just enough to barely cover the rice. Stir often and maintain a gentle simmer, adding more stock as it is absorbed.
After about 8 minutes of cooking, stir in the asparagus stalk pieces (reserve the tips). Continue adding stock and stirring until the rice is al dente, 16β20 minutes total from the first ladle, and the mixture is creamy and flowing.
In the final 2β3 minutes of cooking, stir in the asparagus tips and cook until just tender.
Season with the kosher salt and black pepper, tasting and adjusting as needed depending on the saltiness of your stock.
Remove the pot from the heat and add the remaining 3 tbsp butter and the Parmigiano Reggiano. Beat vigorously for 30β60 seconds until glossy and creamy, adding a splash of hot stock if needed so the risotto relaxes and gently spreads on the plate (all'onda).
Let rest 1 minute, then serve immediately while creamy.