Heat a large skillet over medium heat and add olive oil. When oil is hot, add mushrooms and sautee until golden and soft. Remove mushrooms from pan.

Add butter to pan along with flour. Whisk until your flour roux is a light golden brown (1-2 min).

Whisk in stock then milk and stir until hot and thickened.

Add the mushrooms back to the pan, season with salt and pepper to taste and bring to a simmer. When gravy is at desired consistency, remove from heat (keep in mind it will still thicken slightly as it cools).

It is ready to serve.