Steps
1. Preheat oven to 350°F (175°C). Grease or line a small 6-inch cake pan with parchment paper.
2. In a large bowl, whisk together yogurt, maple syrup, melted butter, egg, vanilla extract, mashed banana, and peanut butter until smooth.
3. In a separate bowl, combine flour, baking powder, baking soda, and salt.
4. Gradually fold the dry ingredients into the wet mixture until just combined.
5. Stir in lemon juice and zest gently.
6. Pour the batter into the prepared pan and evenly sprinkle blueberries on top.
7. Bake for 25-30 minutes, or until the top is set, edges are golden, and a toothpick inserted in the center comes out clean.
8. Remove from oven and cool on a wire rack before slicing and serving.