This. This was one of those recipes. You know, the kind that takes weeks and weeks of testing, where there's always something just a little off. Where the thought of giving up seems so enticing, but you've put so much effort into it already that defeat is not an option.
Let's dive right in, shall we? First was the filling. How do you make a chocolate hazelnut filling? In my first two tries, the custard was cooked with finely ground hazelnuts then strained over and over and over again. It was impossible to strain out the super fine hazelnut meal through a mesh sieve, and the custard was far too thick to strain through a cheesecloth. Third time around, I thought up a brilliant idea of using hazelnut milk instead of whole milk. Unfortunately, nut milk does not have the same properties and chemical composition of real milk. The custard never set with the same amount of egg yolks and cornstarch. The fourth time I added an extra egg yolk and doubled the cornstarch, and while thicker, it still never set. I gathered it had something to do with either the absence of milk proteins or milk fat, but there is a surprising lack of information about the chemistry behind cooking on the internet (if you have a scientific explanation, please message me I'd love to know). Hesitant to add even more thickening agents to the mixture, I then made another version of hazelnut milk, using real milk instead of water, simmering it with ground hazelnuts, and letting the mixture steep before straining. So I guess you could call it a hazelnut milk milk. Ta-da! Success.
Ahem, then there was the whole after-30-minutes-the-donuts-were-greasy problem. Fortunately the internet did have a solution for that: frying in vegetable shortening instead of oil. The short explanation is because vegetable shortening is solid at room temperature, the grease doesn't seep out after frying as it does with liquid oil. One more kink to work through, the dough wasn't quite as soft as I would have liked. The solution: more sugar, more egg, and we finally have a donut I'm proud to share. Cue the sigh of relief, here.
