Cut the pastry in half longways with one piece (the top) being slightly larger than the other. Place the smaller piece on a lightly buttered baking sheet. Spread the mincemeat on top leavig a 2 cm gap around the edge. Top this with cored and peeled apple slices arranged in an overlapping line. Sprinkle the almonds on top.
Fold the other piece of pastry in half lengthways and make cuts along its length from the folded edge to within 2cm of the other edge. Open this out and top the tart, sealing the edges with a pinch. Brush with the egg mixed with the milk.
Bake the jaloousie for 20 minutes then lower the temp to 180C/16Fan/G4 and continue baking for a further 10-15 minutes until crisp and richly golden