Combine milk and yeast in a large bowl and let stand for 5-10 min. Add 2.5 cups flour, 1/3 cup maple syrup, applesauce, flaxseed and salt and start kneading. Gradually add the remaining flour and continue to knead for 7-10 min. Give the dough a round shape in the same bowl, cover with plastic foil and let it rinse in a warm place for about 2 hours.
Prepare the filling. For that ,combine the diced apples (skin removed), raisins, 2 tbsp water and 2 tbsp maple syrup. Shimmer for 5 min stirring occasionally.
Combine the cornstarch with the cinnamon and the remaining water and stir into the apple sauce. Cook for 1-2 min and let it cool completely.
After the dough has doubled in size, punch it down and place it on a floured surface. Cover it with a kitchen towel and let it sit for 10-15 min.
Roll the dough into a 12x18 inch rectangle (leave 1 inch unfilled along the long side). Spread the apple filling over the dough.
Roll up the rectangle along the long side and seal the seam by pinching the end of the roll.
Cut into about 0.5 inch thick slices. Line a tray with parchment paper and place the pieces about 1 inch apart. Cover with a towel and let stand for 45-50 min.
Bake at 375 °F for 30 min.
Optionally brush the rolls with the remaining maple syrup.