Drain the asparagus. Save four sticks for decoration, cut the rest into small pieces.
Mix the asparagus stock, cream, white wine and lime juice.
Put the butter in a saucepan and let it melt over medium heat. Add the flour and mix both ingredients with a whisk to a smooth mass. Let the mixture simmer gently, stirring, until it bubbles up and begins to thicken. Add the liquid mixture to the roux and reheat. Let simmer for 5 minutes. Season to taste with salt and pepper.
In the meantime, cook the spaghetti firm to the bite in plenty of salted water and heat the asparagus.
Serve the spaghetti with the asparagus pieces and decorate with the asparagus stalks. Pour the sauce over it and serve.