1. Asparagus Preparation: Trim woody ends off asparagus and cut into thirds. Blanch in boiling salted water for 2-3 minutes until crisp-tender and bright green. Rinse under cold water, drain, and set aside.
2. Chicken Preparation: Flatten chicken breasts to an even 1/4-inch thickness. Season both sides with garlic powder, salt, and pepper.
3. Searing Chicken: Heat 3 tablespoons olive oil in a large skillet over medium heat. Brown chicken 3-4 minutes per side until golden and cooked through. Transfer to a baking pan and cover to keep warm.
4. Sauce Preparation: In the same skillet, heat 2 tablespoons olive oil over medium heat. Add mushrooms and cook for 1-2 minutes. Incorporate butter, garlic, and onion, cooking until mushrooms are tender and onions translucent. Pour in Madeira wine and beef broth, scraping any browned bits. Add cornstarch mixture, Worcestershire sauce, and thyme. Simmer for 20 minutes until thickened. Stir in whipping cream and simmer for 2 more minutes if using.
5. Combine and Bake: Transfer sauce to a container and keep warm. Arrange asparagus around and over the chicken in the baking pan. Top with mozzarella cheese and broil for 3-4 minutes until cheese is melted and golden. Pour warm sauce over the dish and serve immediately.