1. Butter a shallow baking dish. Butter both sides of each bread slice, using all of butter. Spread marmalade on one side of 6 slices of bread. Take other 6 slices of bread and place them on top of marmalade slices to make 6 sandwiches. Cut each sandwich diagonally in half; arrange sandwich halves in prepared dish.

2. Crack eggs into a bowl. Using the tip of a knife, scrape vanilla seeds from bean halves into bowl and whisk eggs until blended. Add milk, cream, and brown sugar; whisk until well combined. Pour milk mixture evenly over bread and sprinkle lightly with more sugar.

3. Cover and let stand at room temperature until bread soaks up custard, 1 hour. Preheat oven to 350 degrees.

4. Uncover pudding and bake until custard has set, about 50 minutes. Remove from oven and let cool slightly.

5. Serve warm, spooned into individual bowls. Top each serving with a dollop of creme fraiche.