Preheat the oven to 350°F (175°C). Line two baking sheets with parchment paper.
In a large bowl, cream together the softened butter, granulated sugar, and light brown sugar until light and fluffy, about 3 minutes using an electric mixer.
Add the eggs one at a time, beating well after each addition. Mix in the vanilla extract.
In a separate bowl, whisk together the all-purpose flour, unsweetened cocoa powder, baking soda, and salt until well combined.
Gradually add the dry ingredients to the wet ingredients, mixing on low speed until just combined. Do not overmix.
Fold in the semisweet chocolate chips and mini semisweet chocolate chips evenly throughout the dough.
Using a tablespoon or cookie scoop, drop rounded balls of dough about 2 inches apart onto the prepared baking sheets.
Bake in the preheated oven for 10 to 12 minutes, or until the edges are set but the centers still look slightly soft.
Remove the cookies from the oven and allow them to cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.
Serve once cooled or store as directed.