Place the chicken breasts between two sheets of plastic wrap and flatten with a meat mallet.
Put the chopped basil in a bowl with a little flour and oregano, and toss the chicken in it.
Melt 2 tsp of the butter in a frying pan over medium-low heat. Once it stops foaming, brown the chicken on each side for about 3 minutes. Cover and set aside on a plate.
Pour off most of the liquid from the pan and raise the heat. Add a splash of olive oil and quickly sear the asparagus, then remove it.
Keeping the heat high, add the Marsala and a quarter of the stock, and boil for a few minutes. Lower the heat, return the asparagus, add the rest of the stock, and simmer to reduce. Add a teaspoon of butter and coat the chicken with the sauce.