Preheat oven to 350°F (175°C).
Line an 8×8-inch pan with parchment.
Mix oat flour, cocoa powder, and baking powder.
Whisk eggs, Greek yogurt, maple syrup, almond butter, and vanilla.
Combine wet and dry ingredients.
Fold in chocolate chips and walnuts.
Spread evenly into the pan.
Bake for 20–24 minutes.
Cool completely before slicing.
Drizzle with melted chocolate if desired.
