The egg tramezzino, all'uovo, is the most self-contained build in the family, because the filling and the bind are nearly the same gesture. Hard-cooked eggs chopped and folded with mayonnaise produce a soft, rich, faintly sulfurous mass that already behaves like a spread before it ever meets bread. Set between two slices of soft crustless white pancarrè, that mass and the pillowy crumb form a single texture, yielding all the way through, with no contrast of chew anywhere in the bite. The egg brings the body, the savor, and the richness; the mayonnaise binds the egg to itself and the whole to the bread, and seals the crumb so it stays soft. The bread brings structure and a mild backdrop. They lean on each other completely: the egg salad would slump out of an unsealed sandwich, and the bread without that rich filling would be nothing at all. The result is a study in softness held just barely in shape.
Done well, it starts with eggs cooked through but not chalky, the yolks fully set and still tender, chopped fine enough to bind but coarse enough to keep a little texture. The mayonnaise goes in by feel, enough to make the egg cohere into a spreadable mass without sliding, often with a pinch of salt and sometimes a thread of mustard for lift. The bread is fresh, soft to a thumb, trimmed clean of all crust so only the crumb remains. A thin film of the same bind on the inner faces of the bread seals the crumb against the filling's moisture in the window before eating. The egg is mounded toward the center so the triangle domes, fullest in the middle, clean at the cut. A sloppy version uses overcooked gray-ringed eggs, too much mayonnaise, and a wet smear that soaks through; a careful one cooks the eggs right, binds them just enough, centers the dome, and cuts a diagonal that holds its pale cross section.
The close relations each deserve their own article rather than being crowded in here. Fold tuna into the egg and the sandwich gains a savory marine note that pulls it toward a different filling entirely. Lay a few leaves of lettuce or thin tomato over the egg and the moisture math and the crunch change enough to warrant separate treatment. Stir capers or anchovy through the mix and the salt profile shifts the whole build. Stack the egg salad with cured meat and you have left the plain version behind. The tramezzino all'uovo is the unadorned baseline, soft on soft, and it is best read on those terms before any addition.