PreparationFor pineapple marmalade: Bring lemon, pineapple, sugar, and 1/2 cup water to a boil in a medium saucepan. Reduce heat and simmer until pineapple and lemon are soft, 35-45 minutes. Let cool completely. For whipped crème fraîche: Whisk crème fraîche and sugar in a medium bowl until thickened, about 2 minutes. For pancakes and assembly: Preheat oven to 200°F. Whisk flour, salt, eggs, milk, 4 Tbsp. butter, and 1 cup water in a medium bowl. Heat 1/2 tablespoons butter in a medium nonstick skillet over medium-high heat and swirl to coat pan. Pour 1/4 cup batter into pan and place 5-6 banana slices on top. Cook pancake until bottom is golden brown and top looks almost dry, about 2 minutes. Flip and cook until pancake is just set and bananas are golden brown, 1 minute longer. Transfer to a baking sheet; cover loosely with foil and place in oven to keep warm. Repeat with remaining butter, batter, and banana slices, transferring to oven as you work. Serve pancakes with pineapple marmalade and whipped crème fraîche. DO AHEAD: Marmalade can be made 2 weeks ahead. Cover and chill.
PreparationFor pineapple marmalade: Bring lemon, pineapple, sugar, and 1/2 cup water to a boil in a medium saucepan. Reduce heat and simmer until pineapple and lemon are soft, 35-45 minutes. Let cool completely. For whipped crème fraîche: Whisk crème fraîche and sugar in a medium bowl until thickened, about 2 minutes. For pancakes and assembly: Preheat oven to 200°F. Whisk flour, salt, eggs, milk, 4 Tbsp. butter, and 1 cup water in a medium bowl. Heat 1/2 tablespoons butter in a medium nonstick skillet over medium-high heat and swirl to coat pan. Pour 1/4 cup batter into pan and place 5-6 banana slices on top. Cook pancake until bottom is golden brown and top looks almost dry, about 2 minutes. Flip and cook until pancake is just set and bananas are golden brown, 1 minute longer. Transfer to a baking sheet; cover loosely with foil and place in oven to keep warm. Repeat with remaining butter, batter, and banana slices, transferring to oven as you work. Serve pancakes with pineapple marmalade and whipped crème fraîche. DO AHEAD: Marmalade can be made 2 weeks ahead. Cover and chill.