01 - Melt butter in a large skillet over medium heat. Add onion and cook until translucent, approximately 3 minutes.
02 - Incorporate garlic and mushrooms. Stir occasionally until mushrooms are browned and tender, about 8 minutes.
03 - Sprinkle flour over the vegetables, stirring to coat evenly. Cook for 1 to 2 minutes to eliminate raw flour flavor.
04 - Slowly pour in vegetable broth while stirring continuously to avoid lumps.
05 - Stir in milk, soy sauce, Worcestershire sauce, thyme, sage, and black pepper until well combined.
06 - Bring mixture to a gentle simmer, stirring occasionally. Cook for 5 to 7 minutes until desired thickness is reached.
07 - Taste and season with salt as needed.
08 - Serve warm, ideal for mashed potatoes, roasted meats, or vegetables.