In a medium bowl, sift together flour, baking soda, salt, cornstarch, and cinnamon. Set aside.

In a large bowl, cream together butter, brown sugar, and granulated sugar until light and fluffy. Add vanilla and eggs, mix until combined.

Gradually add the dry mixture to the wet mixture, mixing on low speed until combined. The dough should be slightly crumbly.

Cover dough with plastic wrap and chill in the refrigerator for 30 minutes.

Preheat oven to 350°F (175°C). Scoop about 1.5 tablespoons of dough, form into a ball, and make a hole to insert chocolate. Seal the dough back around it.

Roll the filled dough ball in a cinnamon-sugar mixture.

Arrange cookie balls on a lined baking sheet and refrigerate for another 30 minutes.

Bake cookies for 13-15 minutes until edges are golden brown and centers are slightly puffy.

Let cookies rest for 5 minutes, then roll in cinnamon-sugar mixture before transferring to a wire rack to cool.