For cheese sauce, melt butter in large sauce pot, add flour and mix and cook for 1-2 minutes on low heat to make blonde roux. Slowly add cold half and half whisking in between additions to prevent lumps. Cook sauce for 5 minutes, then add heavy cream, cream cheese, smoked cheddar, Dijon mustard, fresh thyme, onion powder, nutmeg, cayenne pepper, season with salt and pepper.