This is a great side dish or even a main meal
Preheat oven to 350F
Blanch the cauliflower in a large pot of boiling water that has been well salted for 5 minutes
Melt 2 tablespoons butter in a medium saucepan over low heat, add the flour, stiring constantly with a roux wisk or wooden spoon- for about 3 minutes- must look like wet sand
Pour hot milk into the roux-butter/flour mix. Whisk constantly... bring to a boil and whisk for another minute or so till it gets thickened-like heavy cream. Add the parm, and 1/2 cup gruyere, nutmeg, salt and pepper
Place the cauliflower in a bake proof dish and pour the Bechamel
Place the half cut hard-boiled eggs and place them in snugly-so they are even with the cauliflower
Mix the remaining cheese and bread crumbs and more salt and pepper-to taste
Sprinkle the bread crumb mixture on the gratin and bake for 30-35 minutes until the top is browned
Let sit for 10 minutes before serving. This is also a great dish to freeze in portions. Just reheat for 15-20 minutes at 350 F