How do I thicken shop-bought fresh custard please?

[CharminglyOdd]

DP has laid out some very specific instructions for a cake (sponge, custard, apple) but I CBA to make custard from scratch and he won't eat Birds (the only one I know how to make thick enough to set) so I was just going to buy a pot of Tesco Finest fresh stuff but I don't know how to make it set. Should I add cornflour or icing sugar please?

You could try heating it and adding cornflour blended with some milk. Not sure it would make it stiff enough so that it wouldn't ooze out of your cake.

Icing sugar will simply oversweeten it.

Why does it have to be in 'cake' format? Surely it would be delicious if you simply layered apples and custard over the sponge?

Really thick custard is not that pleasant, imo.

Thank you :) I am also not sure about whether cornflour would be thick enough. I think DP, who doesn't know how to bake, wants me to emulate the kind of thing his mother makes/continental custard in cakes (he's not English). I guess that's confectioner's custard but the recipe looks even more fiddly than real custard.

TBH he doesn't like cake and I miss baking so any chance that he'll actually eat something I bake I'll jump at even if I think it's weird!

I have used confectioner's custard as a cake filling and it works very well but it has to be good and thick, in fact fairly solid at room temperature. Tesco's Finest fresh custard is very nice but is quite eggy it could split when you heat it unless you're careful. You could try mixing some cornflour (about a dessert spoonful) with a little cold milk until it has dissolved into a smooth paste. Heat the custard gently and stir in the cornflour mix little by little, it should thicken up as it comes to the boil and the extra cornflour should help stabilise it. Let it blip away for a minute or two to cook the cornflour. Gentle heat is the key. Taste it to see if it needs a little more sugar and/or vanilla extract. Cool and use to fill the sponge cakes.

How about creme mousseline? It sets better than just confectioners' custard. Basically it's sugar and eggs whisked to a mousse and then butter added. The bakers in the next village use it for their cream slices.

How about you ask dp's dm for the recipe for her precious ds?

Could you use gelatine to set it?