Return pot to medium-low heat. Add cream cheese, milk, cheddar, yogurt, garlic powder, onion powder, and salt. Stir until smooth.
4 oz low-fat cream cheese, 1/2 cup skim milk, 1/2 cup nonfat shredded cheddar, 1/2 cup nonfat Greek yogurt, 1 tsp garlic powder, 1 tsp onion powder