Set a large heavy-based saucepan over medium-high heat. Add a third of the butter and 1 tbsp of olive oil. When the butter is bubbling, add the sliced leeks and cook, stirring regularly, for 5–6 minutes, taking care not to let them colour.
While the leeks cook, strip the leaves from the chard stalks and rinse them. Slice the stalks into 1 cm pieces and add them to the leeks. Roughly shred the leaves and set them aside. Sweat the chard stalks for a minute or two, then add the rinsed pearled spelt to the pan and stir everything together.
Begin adding the hot stock a couple of ladles at a time, stirring regularly. When half the stock has been used, add the asparagus pieces (except the tips) and the chopped chard leaves. Stir in and continue adding stock as needed. Cook the spelt and vegetables for a further 5 minutes or so.
Stir in the grated cheese and remaining butter, along with the chopped herbs and asparagus tips. If using broad bean tops, pinch some out and add them now; alternatively, you can use pea tops.
Taste the dish and adjust the consistency with a splash more stock—it should be loose. Season with salt and pepper to taste. Spoon the speltotto into bowls, drizzle with the remaining olive oil, and serve immediately.
