Eggless Banana Crumb Muffins

3 very ripe large bananas, mashed
1 cup all purpose flour
½ cup whole-wheat flour
1/3 cup unsalted butter, melted
1 tsp baking powder
½ tsp baking soda
¼ tsp salt
½ tsp cinnamon powder
½ cup brown sugar
¼ cup white sugar
2 tbsp yogurt
1 tsp vanilla essence
½ cup chocolate chips (optional)

For crumb:
1½ tbsp brown sugar
1 tbsp all purpose flour
½ tbsp butter

Preheat oven to 350 degrees F (180 degrees C) and place the oven rack in the middle of the oven.

In a large bowl combine the flours, sugars, baking powd, baking soda, cinnamon pwd, salt and chocolate chips. Use a whisk to combine. Set aside.
In another bowl combine the mashed bananas, yogurt, butter and vanilla. With a wooden spoon, lightly fold the wet ingredients (banana mixture) into the dry ingredients until just combined and batter is thick. Do not over mix the batter.

Prepare crumb by combining together the brown sugar, flour and butter. Keep aside.

Spoon the batter into the prepared muffin liners half way through and sprinkle some crumble on top of each muffin. Bake for about 22-25 minutes or until a toothpick inserted in the center comes out clean.
Place on a wire rack to cool and remove muffins from pan. Serve warm or at room temperature. Makes 12.