Melt butter in a large soup pot over medium heat. Add shallots then saute until tender, 4-5 minutes. Add garlic then saute for 1 minute. Add the cauliflower, fresh dill, seasoned salt, and pepper then stir to coat cauliflower in butter. Add water then place a lid on top and steam cauliflower until tender, 7 minutes, stirring occasionally.
Meanwhile whisk 1/4 cup chicken broth and flour together in a small bowl then set aside. Add remaining 1-1/2 cups chicken broth and milk to the soup pot, season with more pepper, then turn heat up to medium-high and bring soup to simmer, stirring occasionally. Turn heat back down to medium then stream in chicken broth/flour mixture, stir to combine, then simmer until soup is slightly thickened, 5 minutes.
Add cream cheese in three batches, whisking until cream cheese is fully melted and incorporated before adding the next batch. Taste then add salt and pepper if necessary and then let soup sit and thicken off the heat for 10 minutes before serving.