Heat 2 tablespoons of salted butter in a skillet over medium heat. Stir in the mushrooms; cook and stir until softened, about 5 minutes. Set aside.
Meanwhile, melt the cream cheese spread and unsalted butter in a saucepan over medium heat, stirring occasionally. Stir in the milk and Parmesan cheese, mixing until smooth. Add in the garlic, basil, and white pepper. Simmer for 5 minutes, then remove the garlic. Stir in the cooked mushrooms before serving.