Preheat the oven to 350ºF and grease an 8×4 inch loaf pan. Line the bottom and long sides of the pan with pieces of parchment paper with overhanging edges.
In a large bowl, whisk together the coconut flour, protein powder, baking powder, salt, and garlic powder. Make sure to break up any clumps in the coconut flour.
Add the eggs, oil, shredded cheese, and water and stir until well combined. If the batter is overly thick, add more water 1 tablespoon at a time. The batter should be thick but scoopable and spreadable.
Spread in the prepared baking pan and bake 30 to 35 minutes, until the top is just firm to the touch.
Remove and brush with the melted butter and sprinkle with bagel seasoning, if desired. Return to the oven for another 3 to 4 minutes.
Remove and let cool about 30 minutes in the pan, then use the parchment paper to help lift the bread out of the pan before slicing.