Bring a large pot of salted water to a boil. Add pasta and cook until al dente. Darin pasta (reserve some of the pasta water to be used later if needed).
Meanwhile, in a pan add 2 tbsp of butter. Add few drops of olive oil to prevent it from burning.Add the bay leaf. Stir in the flour. Cook for a couple of minutes till the mixtures start to bubble but still white in colour (Don't let it brown).
Add hot cream/milk. Continue to whisk as the sauce thickens. Bring it to a boil,string continuously . Stir in cheese. Lower heat. Add salt and pepper. Remove from heat. Transfer the sauce to a bowl. Cover with a cling wrap and let it cool for later use.
Clean mushrooms. Cut into a thick slice.
In a pan add remaining 1 tbsp butter. Add sliced mushrooms.Sprinkle little salt and pepper. Saute for Couple of minutes. Add white wine and deglaze the pan.(if you are making for kids you can certainely skip wine and add some reserved pasta water to it.)
Add cooked pasta, followed by the sauce prepared above. Sprinkle seasoning.Season with salt and pepper if required(Keep in mind that the sauce, pasta and mushroom has already salt in them).
Add olive. Toss everything. Add reserved pasta water if required to loosen the sauce.