Make the topping by mixing the sugar and cinnamon together. Set aside.
Cream the butter and sugar together until fluffy (1-2 minutes) with an electric mixer. Mix in the egg and vanilla and set aside.
In another bowl, whisk together the flour, cream of tartar, baking soda, cinnamon and salt. Slowly add the dry ingredients to the wet ingredients and mix together on low until well combined.
Using a tablespoon cookie scoop, scoop out the dough into 36 balls. Roll each ball in the cinnamon/sugar mixture and then place each ball into a well-greased mini muffin pan.
Bake for about 12 minutes at 350 degrees or until the edges turn slightly golden brown. Immediately after removing from the oven, make an indention in the top of each cookie by pressing the back of a tablespoon into each cookie cup. (If a tablespoon seems too big, try a 1/2 or 3/4 tablespoon size.)
After cooling for 3-5 minutes, use a knife to gently pop out each cookie cup and then place on a wire rack to cool.
Prepare apple pie filling by chopping up the apples in the filling into small pieces. Use a tablespoon sized cookie scoop to scoop the pie filling into each of the cookie cups. If desired, sprinkle some of the remaining cinnamon/sugar mixture on the top of the pie filling.