Heat butter and olive oil in a large frying pan over medium heat until the butter has melted.
Add the sliced mushrooms and cook for 6–8 minutes, stirring occasionally, until they are golden brown and most of the moisture has evaporated.
Add the minced garlic and cook for 30–60 seconds until fragrant, being careful not to let it burn.
Sprinkle the flour over the mushrooms and stir well for 1 minute to cook out the raw flour taste.
Slowly pour in the stock while stirring continuously until the mixture becomes smooth.
Add the thickened cream, parmesan cheese, Italian herbs, salt, and pepper. Stir until combined.
Reduce the heat and simmer gently for 3–5 minutes until the sauce thickens and becomes creamy.
Serve immediately tossed through cooked pasta, spooned over chicken or steak, or used as the base for a creamy pasta bake.
