Preheat oven to 350 degrees F and line two baking sheets with parchment paper.
In a small saucepan, over low heat (or in the microwave), melt the chocolate chips and butter. Remove from heat and allow to cool.
In a large bowl, or the bowl of a stand mixer (using the whip attachment), combine the eggs, sugar, and vanilla. Whip (with the stand mixer or a handheld electric mixer) on a high speed for about 5 minutes or until the mixture looks fluffy and light.
Pour the bowl of melted chocolate chips and butter into the egg and sugar mixture, mixing on a lower speed until all ingredients are incorporated.
Add the flour, cocoa powder, salt, and baking soda, mixing on low speed until all ingredients are combined. The batter will be a bit thin (not as thick as cookie dough).
Use a spoon or a cookie scoop to drop the cookie dough onto the prepared baking sheets. Place each blob of dough about 2-3 inches apart, as these cookies will spread.
Bake at 350 degrees F for 10 minutes or until the edges of the cookies are firm.
Remove baking sheets from the oven and allow cookies to cool on the baking sheet for 10-15 minutes. Then remove cookies to a wire rack to finish cooling.
Store cookies in an airtight container for up to 4 days.