Prepare the pasta in salted water according to the instructions on the packet. In the meantime, dice the onions and press the garlic through the press.
Cut the bacon into strips and fry them very crispy in a pan without fat, then remove. Sweat the onion and garlic in hot butter, dust the flour over it and sweat lightly. Stir in milk and cream, bring to the boil. Season to taste with salt and pepper.
Put the ricotta in the sauce and melt in it. Add the frozen spinach and let it thaw. Drain the pasta and fold in. Serve sprinkled with bacon.