Preheat the oven to 180 °C (355 °F). Bring a large pot of salted water to the boil and cook 300 g spaghetti or fettuccine until just al dente (2 min under the package time, as it will keep cooking in the oven). Drain and reserve.
Meanwhile, slice 4 large bacon slices into strips. Fry in a dry skillet over medium heat for 4–5 min, until crisp and the fat has rendered.
In a bowl, whisk together 3 eggs, 250 ml sweet cream, 200 ml milk, and 50 g grated parmesan. Season with salt and a generous grind of pepper.
Place the drained pasta and bacon (with its fat) in a greased baking dish, toss briefly, then pour the egg-cream mixture evenly over the top, pressing the pasta down so it is submerged.
Bake for 30 min, until the top is golden and the custard is set. Let rest 5 min before serving.