Put butter in pan with oil in a medium pan, stir until melted. Take off the pot from the stove and add in the flour until it becomes thick and paste like yet creamy. Keep adding flour until the consistency is thick. Put pot back on stove in low heat and add milk, garlic, salt, pepper, parsley. Keep stirring or else it'll leave clumps. Keep stirring until the consistency is creamy. If you want it creamier just add flour. Or if it's too creamy and thick add a little more milk. Just experiment with it until its the consistency you desire. You can actually also add white wine to give it that umph taste