I was going to say pomegranate and see it has already been mentioned.
Brandy snaps and cheese straws - simply can't be arsed and don't see the attraction in any event.
I have made birds custard three times, it has always come out lumpy and bright yellow and tastes awful. What is the point when it's simple pimple to make proper custard which is delicious? Honest question.
On the lasagne point, it is worth it but has to be made in bulk. I usually make a huge ragu, with about 4kg of mince one weekend, we'll have spag bol and I'll freeze some more servings and the remainder of the ragu. Then a week or two later pull.it out of the freezer and make a large quantity of bechamel. Assemble three large lasagne, bake and freeze. The faff isn't worth it for a pound of mince and dish for 4.
Christmas cake and Christmas pudding. However, I think a really good rich fruit cake unadorned at Christmas is usually better quality than the iced confections for an exorbitant price. I have been known to buy a good dark fruitcake and to marzipan and ice it myself.
The overhyped and artificial tasting boozy creams at Christmas. Teaspoon of icing sugar, a half pint or pint of double cream and tablespoon of brandy or suitable sticky works just as well.
Puff pastry. Mine is never as good as jus-rol.
Bread.
Ice-cream
Decorative French Flans - we have a fabulous French Deli close by - I can match the quality but am not prepared to when £20 does it.