To Make the Cake:

1. Preheat the oven to a true 325°F.  Use an oven thermometer to determine whether your oven is accurate.
2. Sift together the flour, baking soda, salt, and cinnamon in a medium bowl and set aside.
3. Add butter to the mixing bowl and mix with a hand mixer or stand mixer until smooth.  Add butter and cream butter and sugar until light and fluffy.
4. Add eggs, one at a time, mixing well after each addition.  Scrape the bowl after the third egg and the final egg.  Add vanilla and mix well.
5. Add half of the flour mixture and mix until combined.  Add all of the apple sauce and mix just until combined.  Add the second half of the flour mixture and mix until almost combined.  
6. Add fresh apples and use a rubber spatula to fold them into the batter and do the last few turns/final bottom scraping of the bowl.
7. Prep a 10- or 12-cup bundt pan with butter and flour.  Put batter into bundt pan and bake at a true 325° for 60-75 minutes.  
8. Remove the cake from the oven and allow to rest for ten minutes.  While the cake is resting, make the simple syrup by combining the sugar and water in a small saucepan and bringing it to a boil.  Once the mixture is boiling, reduce the heat and simmer just until the sugar is completely dissolved.  Remove the mixture from the heat and add the vanilla extract.
9. After the cake has rested for ten minutes, turn it over on a cooling rack, atop a piece of parchment paper.  Brush the simple syrup on the entire cake with a pastry brush.  Allow the cake to cool completely before adding the final glaze.

To Make the Final Glaze: 

1. Combine the confectioner’s sugar, cinnamon, kosher salt, maple syrup, and maple extract (if using) in a medium-sized bowl.  Whisk gently until the mixture is completely combined.  The final mixture should have the consistency of thick honey, and you should be able to pour it.  If it is too thick, you can add maple syrup, 1/4 tsp at a time until it reaches the desired consistency.  
2. Pour or spoon the final glaze over the top of the cake evenly, allowing it to drizzle down the sides.