Preheat your oven to 350°F (175°C) and line a muffin tin with paper liners.
In a mixing bowl, combine all dry ingredients for the muffins. In another bowl, mix the wet ingredients. Combine both mixtures and stir until just blended.
In a separate bowl, mix all crumble topping ingredients until crumbly. Set aside.
Fill muffin tin cups with muffin batter and top with crumble mixture. Bake for 20 minutes or until a toothpick comes out clean.
Let the muffins cool before serving.
Notes
These muffins are best enjoyed fresh. You can store them in an airtight container for a few days.