Preheat oven to 375 degrees F. Coat 12 standard 2 1/2-inch muffin cups with cooking spray. Place raisins in a small bowl and cover with hot water. Set aside.

Whisk whole-wheat flour, all-purpose flour, baking powder, salt and cinnamon in a large bowl. Stir in bran.

Whisk egg, milk, apple butter, brown sugar (or Splenda), oil and molasses in a large bowl until blended. Make a well in the dry ingredients and pour in the wet ingredients. Drain the raisins; add them and the diced apple to the bowl. Stir until just combined. Scoop the batter into the prepared pan (the cups will be very full).

Bake the muffins until the tops spring back when touched lightly, 18 to 22 minutes. Let cool in the pan for 5 minutes. Loosen the edges and turn the muffins out onto a wire rack to cool slightly before serving.

Wrap leftover muffins individually in plastic wrap, place in a plastic storage container or ziplock bag and freeze for up to 1 month. To thaw, remove plastic wrap, wrap in a paper towel and microwave on Defrost for about 2 minutes.