In a small bowl mix the cornflour, sugar, 2 tbsp maple syrup and cinnamon to make a thick paste, season with a pinch of salt. Toss the chopped banana through the mixture.
Unroll the pastry sheet and use a pizza wheel to cut in half lengthways down the centre. Cut each half into 3 equal rectangles so that you have 6 rectangles in total. Turn a piece of pastry so the long side is nearest to you, and fold it in half like a book, to create a fold down the middle. Open the pastry out and spoon the fruit filling onto one side, leaving a boarder of about 1cm around the edge. Brush the beaten egg around the edges and fold the pastry again to encase the filling. Use a fork to seal the edges all the way around, then brush all over with more egg. Poke a few air holes in the top with the fork. Repeat with the remaining pastry and filling. Arrange the pop pies on a baking sheet lined with baking parchment and chill for at least 30 mins, or for up to 24 hrs. Alternatively freeze for up to 2 months.
Heat oven to 200C/180C fan/gas 6. Bake the pop pies for 20 mins, or until the pastry is golden and the filling is bubbling through the holes. Remove from the oven and cool for at least 20 mins. If cooking from frozen, bake for an extra 5 mins. Meanwhile mix the remaining maple syrup with the icing sugar and a pinch of cinnamon and salt to make a thick icing. Spread thinly over the pies and sprinkle with pecans. Eat warm, or cold, for breakfast or drizzle with cream or custard for dessert.