Preheat your oven to 350°F (175°C). This ensures your cookies bake evenly and turn out perfectly soft and fudgy.
In a large mixing bowl, cream together the softened unsalted butter, light brown sugar, and granulated sugar until the mixture is light and fluffy. This should take about 2-3 minutes.
Beat in the eggs, one at a time, mixing until fully incorporated. Then add the vanilla extract and mix until combined.
Add the instant chocolate pudding mix to the wet ingredients. This is the magic ingredient that will take your cookies to the next level! Mix until everything is well combined.
In a separate bowl, sift together the cocoa powder, all-purpose flour, baking soda, and salt (if using). Gradually add this dry mixture to the wet ingredients, mixing until just combined. Be careful not to overmix to keep those cookies soft.
Gently fold in the semi-sweet chocolate chips and chopped dark chocolate until evenly distributed throughout the cookie dough.
Using a cookie scoop, drop heaping tablespoonfuls of dough onto a lined baking sheet, leaving space between each cookie. Bake in the preheated oven for 10-12 minutes, or until the edges are set but the centers are still soft.
Allow the cookies to cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely. This will help them maintain their soft and fudgy texture.
