Drain the pears, but be sure to save the juice.
Cut the pears into small pieces.
Split the trifle sponges in half and sandwich them together with the strawberry jam.
Measure out the sherry in a measuring jug, and then top it up to 150ml with the reserved pear juice. If you prefer your trifle without sherry, you can use all of the pear juice, which should amount to about 150ml.
Take a glass serving dish, approximately 20cm in diameter and 6cm deep.
Place half of the chopped pears in the bottom of the dish.
Follow this with half of the prepared trifle sponges, then add the remaining pears, and finally, the remaining sponges.
Sprinkle the ratafias evenly on top.
Now, pour the sherry and pear juice mixture evenly over the layered ingredients.
Pour the custard over the top layer.
Whip the cream in a separate bowl until it just holds its shape.
Spoon the whipped cream gently over the custard, smoothing it out evenly, or fluffing it up, as you prefer.
Chill the trifle in the refrigerator.
Just before serving, sprinkle the toasted flaked almonds on top.