1. Heat the butter in a medium saucepot over medium heat. Crumble the sausage into the pot, sprinkle with the poultry seasoning. Slowly cook the sausage, breaking it up with a spoon, until it is browned and fat has rendered out. Drain the sausage in a fine mesh strainer over a bowl, reserving the sausage and 1/4 cup of the rendered fat. Add melted butter if there isn't enough fat.

2. Pour the reserved fat back into the pot. Sprinkle the flour over it. Cook, stirring constantly, until the flour loses its raw taste, about 1 minute.

3. Gradually whisk the evaporated milk, half and half, and chicken base into the flour mixture. Cook over medium, whisking constantly, until the sauce thickens, about 5 minutes. Add the reserved sausage into the gravy. Season with salt and pepper, if necessary. Serve over split biscuits.