Turn oven to 400. In large mixing bowl stir whole wheat flour, white flour, baking soda, baking powder, salt, cinnamon and flax. Create a small well in the center of the dry ingredients. In separate bowl lightly whisk eggs, brown sugar, yogurt, banana, applesauce and milk. Pour wet ingredients into the dry ingredient “well”. Gently fold went and dry ingredients together until blended using 12-15 strokes; batter will still be lumpy. Fill muffin cups 3/4 full in greased or lined muffin pan.
<span></span>To make the crumb topping stir flour, sugar, and cinnamon together. Use a fork stir butter into mixture, allowing clumps to form. Top each muffin with 1 T crumb topping.
Bake immediately for 20 minutes or until tops are golden.