Cut the apples in half widthways. Remove and discard cores, then stand the apples in a microwave-safe dish. Break the marzipan into small chunks and mix with the mincemeat and lemon zest. Spoon into the centre of the apples and pour over the lemon juice.
Cover the dish with cling film, pierce several times and microwave on High for 4½ minutes. If you don't have a turntable and the apples are not cooking evenly, turn the dish halfway through.
Remove the cling film and leave to stand for 5 minutes before serving.