In a dutch oven over medium heat melt butter and then add next 3 ingredients (carrot - garlic) and cook for 6-10 minutes or until vegetables are tender.
Stir in pepper flakes and squash and cook for 10 minutes more.
Stir in chicken broth and bring to a simmer.
Stir in crab meat and cooked until heated through.
In a small bowl whisk together flour and a little milk to make a paste and then add remaining milk. Add to soup and cook for another 10 minutes -- DO NOT BOIL.