1/ on your working table, cut the mushrooms into very small pieces (the smallest as you can) with a sharp knife (or mix them)
2/ melt 0.5 oz butter in a small pan, pour the shallots into it and let them cook slowly, covered and without letting them brown, then add the mushrooms and let the mixture dry very slowly without the lid (you get a “dry Duxelles”). Season with salt and pepper and let it cook slowly at low heat during 5 to 10 minutes
3/ cut the shelled hard boiled eggs into 2 halves in the length, extract the yolks and sieve the yolks to get a kind of a powder (keep separately aside the yolks and the empty half whites)
4/ blend the yolks with the mushroom Duxelles, add a soup spoonful of Béchamel sauce and make the mixture boil and finally adjust the seasoning. Add a little semi hot red pepper powder and, off the heat, the parsley : the stuffing is now ready
5/ heat slowly the remaining Béchamel sauce in a pan
6/ put the half empty egg whites into an oven plate and fill them with the stuffing (refer to point 4 above) using either a spoon or a pastry bag
7/ switch on the grill of your oven
8/ end of preparation of the sauce : when the Béchamel sauce is very hot, add the 2 yolks and whisk, then add the grated cheese and whisk again and add a very little of nutmeg and whisk. Take the sauce off the heat and using a small ladle, cover the eggs with the sauce and pour the remaining butter (1.0 oz and melted) butter on them.
9/ let the whole brown under the grill in the oven (to make it a gratin) during a few minutes and serve very hot
This very classic recipe is a base : you can modify the stuffing according to your taste, using foie gras, scallops, scampi, etc…
credits photo : © Asfaux Patrick - A.F.Touch