• Melt butter in large saucepan or dutch oven over medium heat.
• Whisk in flour, salt and nutmeg to make a roux.  Cook over medium heat for 2-3 minutes, stirring constantly.  (This will help cook out any "flour" taste.)
• While whisking briskly, add in milk and chicken broth.  Whisk until combined and smooth.  Remove from heat.
• In separate bowl, mix egg yolks and half-and-half until combined.  Add in 1/4 cup of sauce mixture to egg mixture.  Stir to combine.  Add 3 more quarter-cups of sauce mixture, one at a time, into the egg mixture.  (This is to temper the eggs - raise their temperature slowly - so as not to scramble them.) Then add egg mixture into large pot of sauce mixture and stir to combine.
• Return to heat and cook for 3-4 more minutes over medium heat.
• Turn heat off and stir in cheddar cheese.  Continue to stir until all cheese is melted.
• Allow mixture to cool, and then portion into freezer-safe containers.  Label and date, then freeze.

To re-heat:

• Defrost sauce overnight in refrigerator.  Pour thawed sauce into saucepan and heat over medium heat, stirring frequently.