Melt butter in a 6-quart Dutch oven or large soup pot over medium high heat. Add onions and celery and cook for 4 to 5 minutes or until softened (stirring frequently).
Add garlic and cook until fragrant (about 30 seconds) while continuing to stir.
Slowly sprinkle the flour over the onions and celery while constantly stirring until a thick paste is formed.
Pour in seafood stock and wine, while using a whisk to whisk well until smooth and there are no lumps. Bring to a simmer (stirring frequently).
Add corn, Old Bay Seasoning, nutmeg, sugar, salt, pepper, and bay leaf. Stir to combine. Bring to a simmer and cook for 4 minutes (stirring frequently). Reduce the heat as necessary to maintain a simmer/gentle boil.
Pour in half-and-half while stirring well to combine. Cook and stir for 1 minute, or until heated.
Gently stir in crab meat and cook for an additional 1 to 2 minutes, or until heated through.
Season with additional salt, pepper, nutmeg, or Old Bay Seasoning if desired. Remove and discard bay leaf before serving.