Preheat your oven to 350°F. In a large bowl, whisk together the egg whites and whole eggs until well combined. In a separate bowl, mix the almond flour, psyllium husks, baking powder, xanthan gum, garlic powder, and salt. Melt the butter and add it to the egg mixture along with the boiled water, stirring until smooth. Fold the dry ingredient mixture into the wet ingredients until a thick dough forms—the psyllium husks will help bind everything and create a better texture than regular keto bread.
Divide the dough from Step 1 into 6 equal portions and shape each into an oval roll that will cradle a sausage. Place the rolls on a baking tray lined with parchment paper, spacing them a couple inches apart. Bake for 35 minutes until they're golden brown and set through. The rolls will firm up as they cool, making them sturdy enough to hold the toppings.
While the bread rolls are baking (around the 10-minute mark), place the sausages on a separate baking tray and put them in the oven. Bake for 20-30 minutes until they're cooked through and browned. Timing them to finish around the same time as the rolls will make assembly much smoother.
While everything bakes, prepare the slaw so it's ready to assemble. In a bowl, combine the finely shredded red cabbage, white cabbage, and fresh parsley. Drizzle with olive oil and apple cider vinegar, then toss until evenly coated. I like to let the cabbage slaw sit for a few minutes to soften slightly, which makes it less watery when spooned onto the hot dogs.
Once the bread rolls and sausages are cooked and slightly cooled, carefully split each roll lengthwise or create a pocket for the sausage. Place one cooked sausage into each roll. Top each with a spoonful of the cabbage slaw from Step 4, then drizzle with sugar-free ketchup and yellow mustard. Serve immediately while everything is still warm.