Instructions

1. Set a rack in the center of the oven and preheat to 400°F.
2. In a large bowl, whisk together the all purpose flour, whole wheat flour, baking powder and salt. Set aside.
3. In a medium bowl, whisk together the maple syrup and melted butter. Whisk in the milk, followed by the egg and egg yolk. Add to the dry ingredients and whisk until just smooth. Let the batter rest for 5 minutes.
4. Meanwhile, grease the muffin pan generously with softened butter or oil.
5. Prepare the streusel by combining the first four topping ingredients with a pastry blender or a spoon in a small bowl.
6. Spoon the batter evenly into the prepared pan. The cups will be almost full. Sprinkle with peanut butter streusel.
7. Bake for 10 minutes, then reduce the temperature to 375°F and bake for about 15 minutes more, or until the muffins are golden and a cake tester inserted into the center of a muffin comes out clean.
8. Cool in the pan for 5 minutes, then remove muffins from the pan. Serve warm with butter, or place on a rack to cool.