Cook the macaroni according to the package instructions. Add salt to the boiling water — it makes a big difference to the flavour.
To make the cheese sauce, start by making a roux. Melt the butter in a pan, add the plain flour, and mix well over medium heat. This will thicken the sauce.
Add the salt, garlic, and a little Worcestershire sauce.
Gradually add the warm milk, a little at a time, stirring constantly.
Once all the milk has been added, stir in the sour cream or yoghurt.
Remove the pan from the heat and add the grated cheese, stirring until the cheese has melted.
Mix the cooked macaroni into the sauce, and enjoy!