1. Preheat the oven to 350°F (175°C) and line an 8×8-inch square baking pan with parchment paper.

2. In a large bowl, whisk together the Greek yogurt, peanut butter, honey (or maple syrup), eggs, and vanilla extract until smooth.

3. Add the oat flour, baking powder, and salt, then stir until just combined.

4. Pour the batter into the prepared pan and smooth the top evenly.

5. Bake for 22–28 minutes, or until a toothpick inserted into the center comes out clean.

6. Allow the cake to cool completely before adding the topping.

7. Place the dark chocolate chips and peanut butter in a microwave-safe bowl and heat in 20-second intervals, stirring until smooth.

8. Spread the chocolate fudge evenly over the cooled cake.

9. Refrigerate for 20–30 minutes to set the topping.

10. Slice into 12 squares and serve.