12 ounces cremini mushrooms, cut into thick slices
2 tablespoons butter
1/2 teaspoon fresh-cracked black pepper (plus more for serving)
1/4 teaspoon salt
1 teaspoon lemon juice
3 tablespoons grated Parmesan (plus more for serving)
Bring a large pot of salted water to a boil over medium-high heat and cook noodles until al dente, about 12 minutes or according to directions on the box. Drain and reserve for later.
In a large pot set over medium heat, melt butter. Add flour and whisk to combine, stirring occasionally, for about two minutes or until golden. Whisk in milk, then increase heat to high, whisking constantly as the mixture thickens and comes to a simmer. Reduce heat back to medium, add salt and American cheese. Whisk for about a minute, until American cheese is fully melted, then add Jack cheese, whisking for an additional two minutes until the sauce is smooth and velvety. Add noodles directly to the sauce, and stir with a wooden spoon for about two minutes or until the noodles have soaked up some of the sauce.
In a large pan over high heat, heat the vegetable oil. When the oil starts smoking, add mushrooms to the pan, making sure not to overcrowd. Work in batches if you have to. Let the mushrooms cook for at least one minute untouched, then toss and sauté for an additional three minutes, until thoroughly browned. Reduce heat to medium, then add butter, salt, pepper and lemon juice. Cook for 30 seconds, then add the mixture in the pan to the macaroni along with the Parmesan cheese. Serve with additional Parmesan cheese and fresh cracked black pepper on top.