Bring a large pot of water to a boil, add salt to taste, and cook 6 oz dried linguine according to package instructions until al dente. Drain and keep warm.

While the pasta cooks, melt 2 tablespoons of the 3 tablespoons of butter in a large saucepan over medium heat.

Add 1 cup sliced mushrooms (about 4 medium mushrooms) and 2 cloves minced garlic to the pan. Sauté 2–3 minutes, until the mushrooms are softened and cooked.

In a medium bowl, whisk together 1 cup half and half, 1 cup milk, and 2 tablespoons cornstarch until smooth and free of lumps.

Reduce heat to medium-low. Add about 1/4 cup of the milk mixture to the saucepan, whisking constantly until the sauce begins to thicken. Continue adding the milk mixture in 1/4-cup increments, whisking after each addition and allowing the sauce to thicken before adding more, until all of the milk mixture is incorporated.

After all the milk mixture is added, cook the sauce while stirring for 1 more minute.

Stir in the remaining 1 tablespoon of butter until melted. Taste and season with salt and pepper to taste.

Add the cooked linguine to the saucepan and gently toss or stir until the pasta is evenly coated with the creamy mushroom sauce.

Serve immediately.