Substitute whole milk for water and use it again at the end to create an ultra-creamy sauce that clings perfectly to the shells without any graininess.

Skip pre-shredded cheese and grate cheddar directly before cooking, as anti-caking agents in pre-shredded varieties prevent smooth melting and create a silky sauce.

Keep stirring throughout the milk-cooking process to prevent sticking on the bottom and help the cheese powder emulsify evenly into the milk for maximum creaminess.

Cook the shells for one minute less than the package suggests, as they continue cooking in the residual heat and milk, preventing mushy, overcooked pasta.

Stir in a tablespoon of cold butter at the very end off-heat to add richness, improve sauce coating, and create that restaurant-quality silky finish.