In a saucepan, bring the chicken broth, onion powder, salt, and pepper to a simmer.

In a separate bowl, whisk together the half and half and flour until smooth.

While whisking the broth, slowly pour in the milk and flour mixture and continue whisking for about 3 minutes until the mixture bubbles and thickens.

Remove from heat and stir in chicken, if using.

Refrigerate in a sealed container for up to 1 week.