Gradually add the half and half to the roux, whisking constantly to prevent lumps from forming. Then add in the Carnation evaporated milk. Continue to whisk until the mixture thickens and begins to simmer.
Reduce the heat to low and stir in the cheddar, smoked gouda, and sharp provolone cheeses until melted and smooth.
Season the sauce with salt, black pepper, garlic powder, onion powder, and smoked paprika, adjusting to taste.