Bring a large pot of salted water to a boil and cook the pasta according to the package directions. Drain and keep warm.
Meanwhile, heat a large skillet over medium heat. Add the oil and once hot, add the garlic and sauté for 2-3 minutes, stirring frequently to prevent burning, until lightly browned.
Increase the heat to medium-high. Add the mushrooms and stir to combine. Sauté for 4-5 minutes, or until the mushrooms are lightly browned and tender. Add 1/4 teaspoon of the kosher salt and cook the mushrooms for an additional 1 minute.
Pour in the oat milk, tahini, the remaining 1/4 teaspoon kosher salt, and black pepper to taste. Stir well to combine (I find a silicone spatula is helpful here). Bring the mixture to a simmer over medium-low heat. Cook for 3-5 minutes, or until the sauce has thickened and is very creamy, stirring frequently. Season the sauce to taste with additional salt or pepper as needed.
Add the hot cooked pasta to the skillet and toss to combine, ensuring all of the noodles are coated in the sauce.