1. Heat a large skillet over medium-high heat. Add 1 1/2 teaspoons oil; swirl to coat. Add mushrooms; cook 6 minutes or until liquid evaporates. Remove mushrooms from pan. Add 1 1/2 teaspoons oil to pan; swirl to coat. Add spinach; cook 1 minute or until spinach wilts. Remove from heat.
2. Heat a Dutch oven over medium heat. Add remaining 1 teaspoon oil; swirl to coat. Add shallots and garlic; cook 1 minute, stirring constantly. Combine milk and flour, stirring with a whisk. Add milk mixture, salt, pepper, and nutmeg to pan; bring to a boil, stirring constantly. Cook 3 minutes or until thickened, stirring constantly. Add cheese; stir until cheese melts and the mixture is smooth. Add mushrooms and spinach to milk mixture, and toss gently to coat.