Heat a skillet with 1 tbsp butter. Add in 2 minced garlic and sauté till the aroma arises.
Add in sliced mushrooms and sauté over low flame for 4 to 5 mins, till it softens and browns well. Do not close the pan while cooking.
Transfer into a bowl and keep aside.
Add the remaining 1 tbsp butter to the same pan. Add remaining 2 minced garlic and sauté till the aroma arises.
Add flour and stir well. Cook for few seconds while stirring continuously for the raw smell to go away.
Add red chili flakes, mixed dry herbs and stir.
Slowly add in milk while stirring continuously. Season with salt and pepper to taste.
Cook over low flame for the sauce to thicken a little bit. This should take less than 2 mins.
Add cooked pasta, mushrooms, olive oil and toss well. Add required amount of reserved pasta water to adjust the creamy consistency. You can also add either milk or water instead of pasta water.
Toss well and stir in parsley or coriander leaves.
Serve this creamy mushroom pasta piping hot.