Bring a small pot of water to a boil. Simmer eggs for 9 minutes, then cool in cold water till serving time.
Meanwhile, marinate shallot in vinegar with a pinch of salt and sugar for 10 minutes. Whisk in olive oil to taste, keeping the dressing rather sharp — a 2:1 oil-to-vinegar ratio is good here.
Meanwhile, make the breadcrumbs: heat 2 tablespoons olive oil in a small, heavy skillet over medium heat. Add the breadcrumbs and cook, stirring frequently, until they are crisp and golden brown (about 5 minutes). Be careful not to burn them.
Meanwhile, fry the bacon until crisp.
Wash and lightly dry the spinach leaves. Place them in a large stainless steel bowl and toss lightly with some of the dressing. Mix in bacon and breadcrumbs and season with pepper. Put the bowl over a pan of simmering water and toss continually with tongs while the salad heats. Use a towel to grip the bowl. Remove when the leaves are just wilted and serve immediately.
Peel and quarter eggs, season with salt and pepper, and serve with salad.
Tear about 1/4 of a good loaf of stale bread to make 2 cups breadcrumbs. Pulse in a food processor until crumbs are coarse.
Toast crumbs in about 3 tablespoons olive oil in a large skillet over medium-high heat, tossing frequently, until crunchy and golden brown, about 5 minutes.
Season withsalt and let cool on a paper towel-lined plate. Store airtight at room temperature.