Prep your air fryer: Preheat to 320°F (160°C) for 3–5 minutes. Line the air fryer baking tray or a small, air-fryer-safe pan with parchment, or spray lightly.

Mix dry ingredients: In a bowl, whisk protein powder, oat flour, almond flour, baking powder, salt, and sweetener until evenly combined.

Mix wet ingredients: In another bowl, whisk eggs, Greek yogurt, nut butter, almond milk, and vanilla until smooth. If the nut butter is stiff, microwave it for 15–20 seconds first.

Combine: Fold the dry ingredients into the wet. Stir just until a thick, scoopable batter forms. If it’s too stiff, add 1–2 tablespoons more almond milk. If using chocolate chips, fold them in now.

Spread the batter: Transfer to the lined pan and smooth the top to about 3/4–1 inch thick. Thicker batter yields a softer center.

Air fry: Cook at 320°F (160°C) for 10–14 minutes. Begin checking at 10 minutes. The top should be set and lightly golden, and a toothpick should come out with moist crumbs but not wet batter.

Rest and cool: Let the pan cool in the basket for 5 minutes, then lift the bars out by the parchment to finish cooling. This helps them set and prevents crumbling.

Slice and serve: Cut into 6 large bars for about 28 g protein each. For smaller snacks, cut into 8 and enjoy two when you need a bigger boost.