Preheat the oven to 375°F. Line 2 cookie sheets with parchment paper.
In the bowl of a stand mixer fitted with the paddle attachment, add the butter, cane sugar, light brown sugar, and vanilla extract. Mix on low until combined and there are no chunks of butter.
Add the milk and peanut butter.
Then, add the flour, baking soda, and sea salt and mix on low until combined.
Add the additional cane sugar for the topping into a small bowl.
Using your hands, form the dough into 24 balls and roll in the cane sugar. Place on prepared cookie sheets at least 1-inch apart.
Bake for 13 to 15 minutes or until cracked and set. Let the cookies cool for a few minutes on the baking sheet.
Remove the hearts while the cookies are baking, so they are ready.
Press a chocolate heart into the center of each cookie. Place the cookie sheet in the freezer for about 10 to 20 minutes to prevent the chocolate heart from melting.
Store in an airtight container for up to 7 days.