In the bowl of a stand mixer, or with an electric mixer, cream butter, and sugar on medium speed until light and fluffy (about 3-4 minutes)
Add eggs and beat well
In a medium bowl, whisk together flour, baking powder, and cornstarch
Dissolve the baking soda in the milk
Alternate adding the flour mixture and milk, beating well after each addition
Depending on the size you'd like use a medium to large cookie scoop, placing the cookie dough on a large well-greased cookie sheet or with a silicone mat or parchment paper.
Bake at 350 degrees for 15-18 minutes. Remove when they are lightly browned on the bottom and feel a bit undercooked in the middle.
Allow to cool on a wire rack for 30 minutes
In a microwave safe bowl, add melting chocolate and coconut oil and microwave at 30 second intervals, stirring in between until smooth.
Dip each cookie into the melted chocolate until fully coated and place on parchment paper
Sprinkle crushed candy canes over the top