Pour in 4 cups of low-sodium chicken broth, followed by the cubed russet potatoes and celery root. Sprinkle in the dried thyme, salt, black pepper, paprika, and cayenne pepper. Bring to a boil, then cover and let simmer for 15 minutes.
Add the chopped broccoli and cauliflower florets to the pot. Continue cooking for an additional 5-7 minutes until all the vegetables are tender, stirring occasionally.
In a separate saucepan, melt the remaining 4 tablespoons of butter over medium heat. Whisk in 6 tablespoons of flour, cooking for about 1 minute until smooth. Gradually whisk in 3 cups of milk until thickened.
Stir in ½ cup of half and half into the creamy mixture. Pour this into the pot of cooked vegetables, stirring to combine. Simmer for an extra minute before turning off the heat.
Gradually mix in 2 cups of shredded cheddar cheese, stirring until fully melted and the chowder is rich and creamy.
Notes
This chowder is great for meal prep.
You can substitute vegetable broth for a vegetarian option.