Heat 2 tablespoons butter or oil in a skillet over medium heat
Add 1 small chopped onion and cook until softened
Add 2 to 3 cups sliced mushrooms
Cook until the mushrooms release their liquid and brown
Add 2 minced garlic cloves and cook for 30 seconds
Sprinkle in 2 tablespoons all-purpose flour
Stir and cook for 1 to 2 minutes
Slowly pour in 1 1/2 to 2 cups vegetable broth or beef broth while stirring
Add 1/2 teaspoon salt
Add 1/4 teaspoon black pepper
Add 1/2 teaspoon thyme or parsley
Simmer until thickened, about 3 to 5 minutes
Adjust seasoning to taste
Serve warm over mashed potatoes, meat, or biscuits