Combine half the butter and 1/2 cup brown sugar in a large frying pan over medium-high heat. Cook for 2 minutes or until melted and smooth. Stir in cream and salt flakes and bring to a simmer. Reduce heat to medium and simmer for 3 minutes or until sauce is slightly thickened. Set aside.
Preheat oven to 200°C/180°C fan-forced. Line a baking tray with baking paper. Place 1 pastry sheet on a flat surface and top with second pastry sheet. Using a 23.5cm round plate or bowl, cut a round, discarding trimmings. Using a small, sharp knife and only cutting halfway down into pastry circle, cut a 1cm border around edge. Using the knife tip, remove and discard 1 layer of centre pastry round. Place pastry case on baking tray.
Evenly sprinkle 1 tbs almond meal over centre of pastry, avoiding the border. Arrange apple on top of almond meal, then brush apple with a little salted caramel sauce.
Place flour and remaining almond meal, sugar and butter in a bowl. Using fingertips, rub butter into dry ingredients until coarse crumbs form. Scatter crumble mixture in and around apple. Bake for 25 minutes or until pastry is golden and puffed. Brush pastry border with a little salted caramel sauce.
Serve apple pie topped with ice-cream and drizzled with remaining salted caramel sauce.