01 -
Slice each chicken breast lengthwise into halves, then place between plastic wrap and pound gently to 0.25 inch thickness. Season both sides with kosher salt and freshly ground black pepper.
02 -
Heat olive oil and 1 tablespoon butter in a large skillet over medium-high heat. When hot, add chicken pieces in a single layer without crowding. Cook 3 to 4 minutes per side until golden brown and easily releases from the pan. Remove and set aside.
03 -
Reduce heat to medium and add remaining tablespoon of butter. Add sliced mushrooms and diced onion, stirring occasionally until mushrooms are browned and onions softened, about 5 to 6 minutes. Stir in minced garlic during the last minute, avoiding burning.
04 -
Pour Madeira wine into the skillet, scraping browned bits from the bottom. Add beef stock and bring to a gentle boil. For a thicker sauce, gradually whisk in cornstarch slurry ensuring no lumps form.
05 -
Lower heat and simmer sauce for 8 to 10 minutes until reduced by half and texture is rich. Stir in heavy cream if desired, cooking for an additional 2 minutes. Adjust seasoning with salt and pepper as needed.
06 -
Blanch or steam asparagus until bright green and tender-crisp, approximately 2 to 4 minutes depending on thickness. Drain and set aside to avoid overcooking.
07 -
Return chicken to skillet with sauce and mushrooms. Arrange asparagus on top and scatter mozzarella slices evenly over chicken. Cover briefly or place under broiler for 2 to 3 minutes until cheese is melted, bubbly, and golden.
08 -
Serve immediately topped with extra sauce. Optionally garnish with fresh parsley. Pairs well with mashed potatoes, crusty bread, or buttered noodles.