Place butter and chopped chocolate in a large microwave safe bowl, microwave for 40 seconds, stir and repeat in 30 seconds increments until fully melted. Set aside and let cool completely.
In a small bowl, combine flour, cocoa powder, salt and baking powder. Set aside.
Once the chocolate has cooled start on the cookies. In the bowl of an electric mixer fitted with the wire attachment beat sugar and eggs on high for 2-3 minutes, until light and fluffy.
Add in vanilla extract and melted chocolate/butter; beat on medium for another 1-2 minutes until combined.
Using a rubber spatula, scrape down the sides of the bowl and the wire attachment, then remove it and gently using your spatula stir in the dry ingredients until combined. Fold in remaining Hershey milk chocolate drops. Cover the bowl with plastic wrap and place in the fridge for 6 hours.
Preheat oven to 350 degrees F.
Place parchment paper on an ungreased baking sheet. Wet your hands with cold water and roll the dough into golf size balls, placing those about 2 inches apart. Sprinkle a bit of Himalayan sea salt on top of each dough ball and bake for 12-14 minutes. Remove from oven and let cool for at least 10 minutes before transferring to a wire cooling rack.
Let cookies cool completely before drizzling with white chocolate.
Bring a medium saucepan half filled with water to a boil. Place white chocolate in a medium bowl set over the saucepan of simmering water, let it melt, stirring just a few times. Make sure the bowl doesn't touch the boiling water, to avoid overheating. Remove bowl from heat and using a fork and using a spoon pour melted chocolate on top of the cookies, garnish with sprinkles.
Let stand for 15-20 minutes before serving for the chocolate to settle, or better place cookies in the fridge for the chocolate to harden quicker.