Make batter: Whisk eggs, add mozzarella, almond flour, baking powder, and salt. Let rest 2–3 minutes.
Cook chaffles: Preheat mini waffle maker; cook ~3–4 tbsp batter per chaffle until golden. Make 8 chaffles total. Keep warm.
Form patties: Divide beef into 8 equal portions; form thin patties. Heat oil in skillet and sear 2–3 minutes per side. Add cheddar to melt.
Mix sauce: Whisk sauce ingredients in a bowl. Taste and adjust.
Assemble: Chaffle → shredded lettuce → patty (with cheese) → pickles → 1–1.5 tbsp sauce → chaffle top. Serve with extra sauce for dunking.