I make a thin to medium bechamel sauce with butter and flour. When the flour starts to turn color, I add in a 50/50 mix of cold milk and half&half.
Cook until it thickens. Season to taste with salt and black pepper. I usually put in a little bit of fresh nutmeg.
Cook the sausage separately, drain some of the greaser off, and add to the bechamel sauce. Stir to incorporate, and serve over fresh, hot, cathead biscuits.
I save my bechamel, for tortellini ....