In a large pot over medium heat, melt the butter. Once melted, add the flour and whisk continuously to create a smooth roux. Let the roux cook for about 2-3 minutes to eliminate the raw flour taste.

Gradually pour in the chicken broth while whisking vigorously to avoid lumps. Add the chicken bouillon cubes (if using) and continue whisking until they dissolve into the mixture.

Slowly pour in the whole milk while whisking constantly. Continue to whisk until the mixture is well combined and starts to thicken.

Stir in the celery salt, onion powder, garlic powder, salt, and black pepper. Let the mixture simmer over medium-low heat for about 10-15 minutes, stirring occasionally, until it reaches a condensed consistency.

Give the soup a taste and adjust the seasonings according to your preference. Add more salt, pepper, or other seasonings if needed.

Allow the condensed cream of chicken soup to cool slightly before transferring it to pint-sized jars. Seal the jars tightly and store them in the refrigerator for a few days, or freeze them for longer storage.