In the last post, Larry P. left a comment describing Johnny Iuzzini's deep-fried chocolate ganache "doughnut". I assumed it was from his book Dessert Fourplay, which I own, but have only read cursorily. Sure enough, I found it on pages 170 & 171. I really need to get to know this book better.
As Larry pointed out, Johnny Iuzzini's doughnut features a creamy ganache blended with methylcellulose to hold it together while frying, and sodium alginate to allow it to be encapsulated in a calcium bath. The doughnut are then dipped in egg, coated with panko, and deep fried. Larry successfully executed the doughnuts in this post.
After succeeding at producing a cake with the frosting baked inside, my thoughts immediately turned to an old donut fantasy. One of my most gratifying achievements in baking was making a yeast donut that rivaled those found in donut shops. For awhile, I became a bit obsessed with the idea of making a filled ring donut. I abandoned the idea when I couldn't achieve the desired results.
Revisiting the idea with new hope and armed with a viable technique, I set out to encapsulate the filling and layer it between yeast dough. Then I reasoned that encapsulating might not be necessary as the dough itself would act as a capsule, and that adding methocel to the filling would stabilize it and help it keep it's shape.
The good news is that it worked.
The bad news is that the textures suffered in the process.
The filling-- popcorn-infused cream and fresh corn juice, reduced and enriched with butter-- lost it's fluid creaminess and became more of a custard. That's not necessarily a bad thing, but I preferred the texture before heating. The yeast dough, which is very soft and wet and a challenge to work with, but produces the most ethereally light and fluffy donuts, turned out sodden and heavy. I suspect that the weight of the filling inhibited the final rise and that the moisture that escaped during cooking became trapped inside the dough.
As a control, I fried a round of dough (without the hole) and filled it with the cream (without the methocel) post-cooking by piping it in through a hole poked in the side. The textures were notably better: thin, crisp crust gives way to pillowy-soft dough; creamy filling spills out. This is the recipe that I am including here because, at least for now, I can't improve upon it.
Download recipe: caramel corn donuts