Add the cornstarch, powdered sugar, and flour to the bowl of a stand mixer fitted with the whisk attachment. Mix on low speed for about one minute.

Add the butter and mix on low speed until the flour starts to blend in. Increase to medium high and continue mixing until a smooth dough forms.

Wrap the dough in plastic wrap and refrigerate for 30 minutes.

Preheat the oven to 325° Fahrenheit. Roll the chilled dough on a lightly floured surface to ¼ inch thickness. Cut out the cookies and place them on a prepared baking sheet, leaving about 1½ inches of space between each one.

Bake for 15 to 18 minutes until the edges are lightly golden and the tops appear dry. Cool on the baking sheet for five minutes, then transfer to a wire rack to cool completely.

Make the caramel by adding the sweetened condensed milk, butter, brown sugar, corn syrup, vanilla, and salt to a medium saucepan. Cook over medium heat, whisking constantly, until the mixture bubbles and thickens. This takes about four to five minutes. Remove from the heat and let it cool in the pan for about 15 minutes until slightly firm.

Whisk the cooled caramel until smooth. Spoon one to two teaspoons onto each cooled cookie. Let the caramel set for about ten minutes.

Add the chocolate chips to a small bowl. Heat the heavy cream in the microwave until steaming. This usually takes one to two minutes. Pour the hot cream over the chocolate and let it sit for five minutes.

Whisk the chocolate and cream until smooth to form a ganache. Let it cool for about five minutes. Spoon about one teaspoon of ganache over the caramel on each cookie. Allow the cookies to set for five minutes before serving.