I was looking up sugars and sweeteners and then caramel, toffee, and butterscotch, and when I read what "cinder toffee" is (also named honeycomb, sponge), I realized that's sort of the inverse of what I did with bread today.
Yesterday I cooked and baked all day. I was really in the mood for it. I made bean dip, and beans, and pasta and rice to freeze, and bread, and flatbread with seeds. I chopped carrots too.
Anyway, today I made more bean dip and made a loaf of bread that did what the cinder toffee does. It says cinder toffee gets bubbles in the sugar because of the baking soda and vinegar added to it, so it bubbles and has holes. I made a wheat bread and crushed some sugar cubes but then with the hard lumps I had leftover, I decided to embed them inside the dough after it was kneaded and find out what happens. It was a yeast bread but I added a small touch of baking soda and my cider salsa. What happened, is there was a little bubble on the top of the crust and when I cut a slice, inside, it was a bubble and crevass where one bit of sugar lump had been. So it basically makes bubbles and holes inside of the bread, sort of looking like a sourdough. But it's only where the sugar was placed, specifically, that a little interior bubble is created. So where cider toffee is sugar with baking soda and vinegar added, this bread gets the bubbles specifically where the sugar lumps are. I only used a few. Maybe next time I'll use a lot and see what happens.