Heat the olive oil in a large skillet over medium-high heat, then add butter and let it melt.

Cook half mushrooms: Add half the mushrooms and cook for 2 mins. Add half the salt and pepper, then continue to cook for another 2 mins until most mushrooms are becoming golden. Then add half the garlic and cook until mushrooms are fully golden, and remove to a plate.

Cook remaining mushrooms: Melt remaining butter, then cook remaining mushrooms per above (adding salt & pepper partway through, and garlic towards the end). Remove to a plate.

Lower heat to medium. In the same skillet, melt the butter.

Add flour and stir continuously for 1 1/2 minutes so the roux doesn't burn. Don't worry if the mixture is a bit dry and sandy, it depends how much fat is left from the mushrooms.

While stirring, slowly pour in the beef stock. This should avoid lumps in the gravy. If there are lumps, just whisk vigorously to dissolve them.

Cook for 3 to 4 minutes, or until it thickens to a thin-syrup consistency. Stir every now and then at first, then more regularly as the gravy thickens so it doesn't burn on the base of the skillet.

Stir in cooked mushrooms, cook for a further 1 minute. Taste and add more salt if needed (if using unsalted homemade stock, you will need more).

Pour into a gravy jug and serve with everything! It's particularly great and very Aussie poured over schnitzel with a side of rosti or chips! Otherwise serve with steak, simple pan-seared chops or chicken, sprinkled with salt and pepper before cooking.