Heat up a pot on medium heat, once hot, add oil followed by garlic and chopped jalapenos. Saute for a couple of minutes.
Add sliced mushrooms and saute for 2 minutes until soft and slightly brown.
Once butter melts, add all-purpose white flour.
Stir the flour into the butter. Cook for a minute. This forms a roux which will help thicken the sauce.
Very, very slowly add the milk a little bit at a time. Now you are tempering the milk to avoid any curdling. Keep stirring as you add little milk at a time.
A few minutes later, you should have a thick sauce.
Add garlic powder, black pepper, and salt to taste.
At this time, add pasta to your boiling water and cook according to package instructions. I prefer medium shells for this recipe, but elbow macaroni will work great too.
Turn off the gas and add the cheese a little bit at a time to avoid curdling. Add 1 1/4 cups of Gruyere and 1 1/4 cups of cheddar cheese a little bit at a time. Keep stirring as you add a little cheese at a time.
Now add 2 tbsp truffle oil - you can start with 1 tbsp and see if you need more. Stir well.
Drain the pasta completely so there is no water.
Add a little pasta at a time to the truffle sauce and mix.
This is what you should have.