1-Heat 1 tablespoon olive oil in a large skillet over medium-high heat, then add 45 grams (3 tablespoons) unsalted butter and let it melt.

2-Cook half the 400 grams (14 ounces) sliced mushrooms with half the 1/4 teaspoon salt and half the 1/8 teaspoon black pepper for about 4 minutes, adding half the 1 1/2 teaspoons finely minced garlic near the end until the mushrooms turn golden; remove them to a plate.

3-Melt the remaining 45 grams unsalted butter and repeat the process with the rest of the mushrooms, salt, pepper, and garlic, then remove to the plate.

4-Lower the heat to medium; in the same skillet, melt 30 grams (2 tablespoons) unsalted butter.

5-Add 4 tablespoons plain/all-purpose flour and stir continuously for 1 1/2 minutes to form a roux without burning.

6-Slowly pour in 2 cups beef stock or broth while stirring or whisking to avoid lumps.

7-Cook for 3 to 4 minutes until the gravy thickens to a thin-syrup consistency, stirring frequently to prevent burning.

8-Stir in the cooked mushrooms and cook for an additional minute. Adjust salt as needed.

9-Pour the gravy into a gravy jug and serve hot.