Preheat oven to 325 degrees (F). Line two large baking sheets with parchment paper, lightly spray them with non-stick spray, and set aside.
Place the semi-sweet chocolate chips and butter in a small, microwave-safe bowl. Heat them in the microwave for 15-second increments, mixing in between each, until butter and chocolate are completely melted and can easily be whisked smooth. Set aside.
In a medium-sized bowl, whisk together the flour, cocoa powder, baking powder, and salt. Set aside.
In a separate medium-sized bowl, whisk together the granulated sugar, light brown sugar, eggs, milk, and vanilla.
Add the dry ingredients into the wet ingredients, and stir to combine. Be sure not to overmix!
Fold in the chocolate and butter mixture and the dark chocolate chips into the batter, stirring until just combined.
Scoop 1/4 cupfuls of the batter on the prepared baking sheets. Place pans in the oven, reduce heat to 300 degrees, and bake for 14 to 16 minutes.
Allow cookies to completely cool on the baking sheet before removing to dip in glaze.
Place a large piece of parchment paper on top of a flat surface. Combine the chopped chocolate and oil in a large microwave dish. Heat on low until chocolate is completely melted, stirring almost constantly.
Dip half of each cooled cookie into the chocolate glaze, allowing any excess chocolate to drip back into the pot before transferring it to the prepared piece of parchment. Decorate the wet chocolate with any of the recommended toppings, then set aside and allow the chocolate to set; about 20 minutes.