cook the macaroni in a pan of boiling, salted water (i always season the water with some bouillon powder, but do as you like). in the meantime heat a small frying pan, add olive oil and sliced shallots and bacon. fry until softened and slightly browned. take off heat but keep warm.
heat the cream in a small pan, season with bouillon powder, freshly ground pepper and fresh nutmeg.
drain the macaroni and put half of it into a large serving dish (or like i did in a pan that will keep it warm). sprinkle half of the grated cheese on top, cover with macaroni and top with the rest of the cheese and the onions and bacon. pour the warm cream over and garnish with chive. cover and let rest for about 5 minutes so the cheese can melt and it gets all creamy and wonderful.
if you have any leftovers (i doubt that...), you can fry this in a small skillet until golden brown. you wont need any butter or oil to do this, the cheese and cream will make sure it will turn golden brown.