Preheat the oven to 350°F.

Melt the butter and chocolate together either in the microwave or in a saucepan. If melting in the microwave, place the chopped chocolate in a microwave-safe bowl. Put the butter over the chocolate, then microwave for 45-60 seconds, depending on the power of your microwave. Stir, then heat in 15 second increments, until the butter is completely melted. Stir to melt the chocolte until completely smooth. If using a saucepan, place the chopped chocolate in a medium heat-proof bowl. Melt the butter in a small saucepan over medium heat. Pour the melted butter over the chocolate chips into the mixing bowl. Let sit for 2-3 minutes then stir to melt the chocolate until completely smooth.

Sift the cocoa powder over the melted chocolate and add the vanilla extract, whisking until smooth.

In a separate large mixing bowl with a hand mixer or a stand mixer with the whisk attachment, whip the eggs and sugars together over medium-high speed for 4-5 minutes, until very pale and fluffy.

Pour the melted chocolate mixture into the whipped eggs, mixing until combined.

Sift the dry ingredients into the batter and fold the batter until completely mixed. It will seem very soft for cookie dough.

Use a medium cookie scoop to scoop a ball of about 2 tablespoons of dough onto a parchment-lined baking sheet, spacing them 2-inches apart. See note about freezing cookie dough, if desired.

Bake for 9-11 minutes, until the cookies are puffy, the edges are just crisp when gently touched, and the center still look gooey and underbaked. Remove from oven and let cool on the baking sheet for 5 minutes, then use a thin metal spatula to transfer to the cookies to a wire rack to cool.

Enjoy warm or let cool completely.