Combine flour, baking powder, salt and baking soda in a medium bowl and mix well. Stir in applesauce. Add buttermilk and stir just until blended.
Knead the dough on a lightly floured surface until smooth. Roll dough into a 15 x 8-inch rectangle.
Preheat the oven to 400°F. Grease with cooking spray a 9-inch round baking pan lightly.
Spread sweetened condensed milk over the dough. Combine granulated sugar and cinnamon in a small bowl and mix well. Sprinkle over sweetened condensed milk. Roll up rectangle, jelly roll fashion, starting from one long side. Pinch seam to seal.
Cut the roll into 1 1⁄2-inch slices. Arrange the slices, cut side up, in prepared baking pan. Bake until lightly browned, about 15 to 20 minutes. Remove from oven. Pour milk over the top, if desired. Serve hot.