Ham, gruyère, dijon mustard, and béchamel sauce are sandwiched between two slices of bread, coated in even more béchamel and cheese, and broiled until the top is melty and blistered.
Serve with slices of onion and hot sauce (a smooth cayenne variety ... Drain and rinse with either method, then add them to a large pot with the water, broth and the ham bone. You can add salt if you ...