My vaguely bread like stuff has flour just little and lots of gluten and other stuff… But if you want some simple bread, I found the almond ones pretty nice. I don’t remember the ratio but not much ground almond per egg, that was good And not bread like, of course, one needs gluten and yeast for that and I never was okay with it without some starch… And even so, it’s not like “normal” bread (thankfully, I don’t like breads with lots of flour and no eggs!), just somewhat similar and it raises and everything.
I experimented with various recipes (more like for cakes, bread rarely was important for me) and sometimes it did what yours did I think it happened when my stuff had too little flour or when I didn’t whip the eggs for something that was good when I did so… Or when I skipped baking soda but you added baking powder, many times more than what I ever added (1/4 teaspoon probably would ruin the taste already, be it baking powder or baking soda, I am sensitive to that but I found that a tiny bit always worked. no idea why all the recipes use so much).
The butter seems excessive too. I use that amount of fat for 2 eggs but with very much other things, about 200g “flour” (gluten, fiber, oily seeds, tiny coconut flour - it’s never good in bigger amounts though some people like that too… I definitely don’t and it’s sweet and coconut tasting anyway, not good for a bread unless we want it sweet and coconut-y. coconutty? :D)… But that’s a raising bread with yeast…
Oh, microwave, of course. Use the oven, maybe? Some doughs just don’t work in the microwave. But it’s possible there are various issues.
This collapse thing is done by my egg sponge cakes (100% eggs but I need to call them somehow and they are sponge cakes just without the flour and sugar). Some flour solves it, flour is in a wide sense, fiber works but fiber is usually tasteless or not nice tasting so it doesn’t do good to the taste when used alone and not in super tiny amounts. Fiber and some oily seed, that’s better.
But my sponge cakes are nice when collapsed too. As the egg is whipped and I bake them in the oven. The rubbery microwave thing is less nice though the taste may be good if the ingredients are right.
I am not sure I helped any but you are welcome to my braindump. I am a bit far from baking now since I try to stay close to carnivore… But I still have my moments when I have off times.
Fortunately eggs are great as bread for me, I can put some spread on my sponge cake muffins… They are nothing like bread but not everyone wants that, often the role (as a base for things on it) and some properties (dry, somewhat fluffy thing… in its collapsed way) is enough.