Apple Pie Filling
In a medium saucepan over medium heat, melt the butter. Add apple slices, brown sugar, cornstarch, and cinnamon.
Heat until the mixture starts to bubble, then cook and stir for about 5 minutes until the apples soften and the filling thickens. Set aside to cool completely.
Salted Caramel
In a small saucepan over medium heat, melt the sugar until it turns an amber color. This takes about 30 seconds; remove from heat immediately.
Gradually add half the cubed butter and whisk until melted. Add the remaining butter, stirring carefully as the mixture bubbles up.
Slowly add half the heavy cream and whisk, then add the remaining cream. Stir in vanilla and salt. Let cool completely.
Cinnamon Cookies
In a medium bowl, combine flour, baking powder, cinnamon, cornstarch, and salt.
In a large bowl, whisk together melted butter, brown sugar, granulated sugar, vanilla, and eggs until smooth.
Add dry ingredients and mix with a spatula until just combined. Let the dough rest for 10 minutes.
Preheat oven to 350°F (175°C). Line two cookie sheets with parchment paper.
Scoop dough into balls and place on the cookie sheet. Press a circle into the dough balls with a measuring cup or spice jar, then shape into a neat circle.
Bake for 11 minutes, remove from the oven and press the circle indentation again, then bake for an additional 1-3 minutes until edges are golden. Cool on a rack.
Brush cookies with melted butter, then roll edges in cinnamon sugar.
Assembly
Fill each cookie indentation with apple pie filling, and drizzle salted caramel over the top.