Melt the butter in a saucepan over medium-high heat.

Add the celery and green onions to the melted butter and sauté until softened.

Stir in the flour and sauté for another minute.

Heat the milk until warm and then add it to the saucepan, whisking to combine and eliminate lumps.

Whisk in the heavy cream, tomato paste, and Old Bay Seasoning.

Bring to a low simmer and cook until the bisque thickens.

Stir in the crab meat and shrimp and heat until the meat is heated through.

Top with fresh parsley as a garnish.