Preheat the oven to 350°F (175°C) and prepare a muffin tin by spraying it with baking spray to prevent sticking.

Roll out the pie dough on a floured surface, then cut it into 2-inch circles. Place each circle into the prepared muffin wells, forming a lovely cookie base.

Prepare the apples by peeling, coring, and finely dicing them, then set them aside.

Cook the diced apples in a medium saucepan over medium heat with sugar, apple cider vinegar, and corn starch. Stir and let simmer for about 15 minutes until the apples begin to soften and the mixture thickens.

Fill each pie crust with a tablespoon of the warm apple filling, ensuring even distribution among all the cookie bases.

Mix the streusel topping by combining flour, brown sugar, oats, and a pinch of salt in a bowl. Pour in the melted butter and stir until everything is well combined and crumbly.

Top each cookie with a generous tablespoon of the streusel mixture, pressing it gently on top of the apple filling.

Bake in the preheated oven for 17-19 minutes or until the streusel is golden brown.

Cool them in the muffin tin for about 10 minutes before gently removing and transferring to a wire rack.