2 tablespoons maple syrup, plus extra for drizzling
Unroll a pastry sheet, keeping the remainder covered with a damp but not wet cloth. Brush all over with some butter, then sift over 1 tablespoon of the icing sugar and scatter with one-quarter of the pecans. Cut in half and place a banana quarter along both shorter ends. Fold in the long edges and roll up. Place on a baking sheet and repeat with the remaining pastry.
Brush all over with more butter, then cook in a preheated oven, 200°C (400°F), Gas Mark 6, for 12–15 minutes until crisp and golden.
Mix the mascarpone with the maple syrup and serve alongside the pastries with more maple syrup drizzled over.