In a medium bowl, whisk the flour, cornstarch, baking powder and salt; set aside.
Using an electric mixer, in a separate large bowl beat the butter and sugar until creamy. Turn mixer to low and beat in egg and vanilla extract until completely combined.
Slowly add the flour mixture into the butter mixture and mix until combined. Add milk and stir again until combined.
Cover bowl tightly and let chill in fridge at least 1 hour or overnight.
Preheat oven to 350°F. Line two baking sheets with parchment paper and set aside.
Once chilled, roll dough into 1 inch balls and place on prepared baking sheet, spacing cookies at least 2" apart. Bake for 11-12 minutes or until cookies are light golden brown around the edges.
In another small bowl, melt the chocolate bark in the microwave, start with 30 seconds, stir, then heat in 15 second increments until the chocolate is completely melted.
Dip each cookie halfway into the melted chocolate and place on wax paper until dry to touch. Serve and enjoy!
Notes
These cookies will stay fresh for up to 5 days if stored in an airtight container at room temperature. Or in the fridge if you like your chocolate chilled For longer storage, place them in an airtight container or freezer bag and freeze for up to 3 months. Thaw at room temperature before serving.