Heat butter in a pan.
When the butter is melted, add chopped garlic and saute it for a minute.
Add the chopped onions and saute till translucent.
Add the chopped mushrooms.
Saute till they are cooked and they shrink.
Add the all-purpose flour (maida ) and saute till fragrant.
Add milk and mix well. Cook stirring in between and cook the mixture on medium heat.
Add the cheddar cheese slice. (If you do not have cheddar cheese, you can use grated processed or mozzarella cheese around 1/4 th cup). Mix well and let the cheese melt. Cook on medium heat.
When the mixture starts to thicken add salt and pepper.
Cook till the mixture is thickened.
Remove the mixture in a bowl.
With the help of a stick blender or mixer blend the mixture into a smooth paste. If you want the sauce to have chunks of mushroom then do not blend the mixture.
The creamy mushroom sauce is ready.
Heat butter in a pan.
Add cooked pasta and salt to it. Mix well.
Add the prepared mushroom sauce and toss the pasta well.
Simmer for a minute and the pasta in a creamy mushroom sauce is ready to serve.
Sprinkle some dried or fresh parsley and grated parmesan cheese over the pasta and serve it hot.