Heat the olive oil in a small teflon pan. Add the beaten eggs and drag them around the pan, allowing the egg to cook evenly.
Remove the pan from the heat at this point as the egg starts to set. Quickly add the asparagus, shallot, salt, pepper and freshly grated parmesan.
Up end the frittata on to a serving plate.
Return the pan to the heat. Add the butter and cook it until it goes a dark nutty brown.
Add the sage and a pinch of sea salt and pour over the frittata.
Finish with a little more parmesan.