Try adding 1 part butter to 1 part fat, the roux develops more consistently. Next, instead of 2 cups of cold milk, try 1 cup of simmering, scorched whole milk (trust me) and add more as it thickens. The result will be a silky, rich gravy with plenty of flavor in its own right, but that screams for Cayenne. Keep it up, you’ll be a Southern Belle in no time!