In a large pot, boil water and cook 1 kilogram of fettuccine pasta following package directions until al dente (around 8-10 minutes). Drain and set aside.
While pasta is cooking, fry 250g bacon in a deep pan until crispy. Remove bacon, let it cool then chop into pieces. Keep the bacon oil in the pan.
Using the same pan with bacon oil, cook minced garlic until light golden. Add minced onions and cook until clear and soft, about 2-3 minutes.
In a bowl, dissolve 2 packs of Knorr cream of mushroom soup in 1200ml room temperature water. Mix well until there are no lumps.
Add the sliced mushrooms to the pan with garlic and onions. Cook for 2-3 minutes, stirring occasionally. Pour in the dissolved mushroom soup and evaporated milk. Keep stirring to prevent sticking.
Pour in the chilled all-purpose cream. Stir continuously while bringing to a gentle simmer. The sauce will slowly thicken as it heats – don't worry if it seems a bit thin at first as it will thicken more when cooling.
Add back the chopped bacon. Stir in 1 tablespoon sugar and a pinch of white pepper. Taste the sauce before adding any salt since the mushroom soup is already salty.
Add your cooked pasta to the sauce. Mix everything well until all the pasta is coated with the creamy sauce.
Add half of your grated cheese while everything is still very hot. Mix well until the cheese melts into the sauce.
Transfer to your serving dish. Top with remaining cheese and sprinkle with chopped parsley if you like. Best served hot with garlic bread.
For better results, serve within an hour while the sauce is at its creamiest. If you need to reheat, do it slowly over low heat and add a little milk if the sauce is too thick.