First, preheat your mini waffle iron or a classic style waffle maker. Avoid using a deep Belgian-style iron for these waffles to get the best crispy texture.
In a large bowl, whisk the two egg whites with the salt and cream of tartar until they form firm, fluffy peaks. Set aside.
In a separate large bowl, gently whisk together the almond flour, the 1/4 cup sweetener for the waffles, and the baking powder until well combined.
Now, stir in the room-temperature almond milk, the single egg yolk, a splash of avocado oil, and fragrant vanilla extract into the dry mixture until everything is smoothly blended.
Carefully fold the whipped egg whites into the almond flour mixture. Be gentle and stop folding as soon as no streaks remain, to keep the batter light and airy.
Lightly grease your preheated waffle iron. Spoon about 3 to 4 tablespoons of batter into each mini waffle well or section of your larger waffle iron. Cook undisturbed for 4 to 5 minutes until golden brown and crispy.
Once cooked, gently remove the waffles and place them on a wire rack set over a rimmed baking sheet. For extra crispiness, you can pop the baking sheet into a warm 200°F oven for 10-15 minutes while you finish cooking the rest. Remember to re-grease your waffle iron between batches!
In a shallow bowl, whisk together the 1/3 cup granular sweetener and the fragrant cinnamon for your coating.
Lightly brush each warm waffle with melted butter on both sides, then gently dip each into the cinnamon 'sugar' mixture to coat evenly.
Serve your delicious Keto Churro Waffles immediately for a delightful, healthy treat!