
Add butter, and melt over MED heat. Once melted, add flour, salt, pepper, thyme, and cayenne and whisk to combine.
Cook flour/butter mixture for 1-2 minutes.
Slowly pour in milk, about 1/2 cup at a time, whisking after each addition, until all milk has been added and no lumps remain.
Bring to a vigorous simmer, whisking frequently. Allow to simmer for about 3 - 5 minutes, or until gravy is smooth, creamy and thickened to your liking.
If gravy gets too thick, add a splash of milk or water to thin it out.