Oatmeal-Applesauce Cookies - to sandwich or not?

These cookies are great alone or, using the optional ingredients, take them to the next level as sandwich cookies.  Either way, you cannot miss.  Thanks to my wonderful Hubby for suggesting the caramel filling option.

  4 Tbl Unsalted Butter, melted                                                  1/4 Tsp Coarse Salt

  1 1/2 Cups Light Brown Sugar,                                                1/2 Tsp Cinnamon

  -Packed                                                                                 1/4 Tsp Nutmeg

  1 Large Egg                                                                          --Optional--

  1/2 Cup Applesauce                                                                1 Cup Light Brown Sugar, Packed

  2 Cups Old-Fashioned Oatmeal                                                1/2 Cup Heavy Whipping Cream

  1 1/4 Cup Flour                                                                       2 Tbl Light Corn Syrup

  1/2 Tsp Baking Soda                                                                1 Tsp Vanilla

  1/4 Tsp Baking Powder                                                           

Preheat oven to 350.  Put butter and sugars in the bowl of an electric mixer and mix until fluffy.  Add egg and applesauce, mix until well blended, 2 to 3 minutes. Mix in oats, flour, baking soda, baking powder, salt, cinnamon and nutmeg.  Drop dough onto baking sheets lined with parchment paper, spacing 2 inches apart. Bake cookies until golden and just set, 13 to 15 minutes. Let cool on sheets 5 minutes. Transfer cookies to a wire rack set over parchment paper; let cool completely.

Optional:

Combine all optional ingredients except vanilla, stir to combine over medium heat.  Bring to a boil and boil gently for 3 minutes.    Remove from heat and stir in 1 tsp vanilla.  Cool completely and use as a filling between two cookies.