Warm the oil in a deep cast-iron skillet or Dutch oven set over medium heat. Using your hands, gently mound beef into 6 balls, and add to skillet. Let brown undisturbed, for 4 minutes, season lightly with salt, then flip and brown another 3 minutes. Transfer browned meat patties to a cutting board, and wipe skillet out completely.
Add the bacon, and allow to render and crisp slightly over medium-low heat, about 6 minutes. Add the carrot, celeriac, and onion. Cook until softened and beginning to brown, stirring occasionally for 6-8 minutes. Meanwhile, finely chop the browned beef.
Add the beef and wine to the skillet, and cook over low heat until the wine is completely evaporated, about 12 minutes. Stir in the tomato paste and bay leaf, and cook until slightly darkened, another 5 minutes. Add the milk, stock, and a few gratings of nutmeg, and reduce the heat to low. Allow to cook at a bare simmer for 2 hours. Serve over pasta or polenta.