Preheat your oven to 350°F.

In a stand mixer, blend the butter and sugars until you get a light and fluffy mixture.

Add the eggs, corn syrup, and vanilla extract, mixing until well combined.

Next, mix in the flour, cocoa powder, cornstarch, baking soda, and salt until you form a soft chocolate cookie dough.

Divide the dough into 12 portions, using a bit less than 1/2 cup per portion. Roll each into a ball and flatten slightly like a hockey puck. Place 6 cookies per tray on parchment paper or a silicone mat.

Bake for 15-17 minutes until the cookies start to crack and the centers no longer look wet.

While the cookies bake, prepare the fudge frosting. Heat the heavy cream in a microwave-safe bowl for 1 1/2 minutes or until boiling.

Add the chocolate chips to the hot cream, ensuring they are fully submerged. Let sit for 3 minutes.

After 3 minutes, whisk the mixture until smooth and set aside to cool.

Once the cookies are done, let them cool on the pan for about 10 minutes. Spoon the frosting onto each cookie and sprinkle with rainbow-coated chocolate chips while the frosting is still wet.

Enjoy your warm, fudgy cookies!