Place a tablespoon of butter in a microwave-safe cereal bowl (the bottom should measure 3.5 - 4 inches). Microwave until melted, about 30 seconds. Allow to slightly cool.
Using a fork, mix in one egg, 1 tablespoon of coconut flour, and ¼ teaspoon of baking powder. Microwave on high for 90 seconds.
Allow the bread to cool slightly, then carefully slice it into two slices.
Cook the egg and toast the bread:
Heat a nonstick skillet over medium heat. Spray it with olive oil spray. Break one egg into the skillet (use a greased egg ring or an egg pan if you want a round shape). Cook on both sides until done to your liking.
Add the two slices of bread, lightly browning them on each side.
Assemble the sandwich:
Place one slice of bread on a plate. Top it with a slice of cheese, a slice of ham, and a fried egg. Place the second slice of bread on top. Serve immediately.
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Notes
When making this recipe, I make the 90-second keto bread in a slightly larger bowl (4 inches on the bottom) than the original recipe calls for. This ensures large enough bread slices to accommodate the filling. Although it also means thinner bread slices.
When I feel like splurging, I make two keto breads. I then use one as the bottom layer and one as the top layer of the sandwich. So rather than make one bread and slice it into two thin slices, I make two breads. This gives me a thick, substantial sandwich.
You can store this sandwich, wrapped in plastic wrap, in the fridge for 1-2 days and reheat it in the microwave (remove the wrap first). But ideally, it should be eaten fresh.