Preheat your oven to 375°F (190°C). Grease a 9-inch springform pan and line the bottom with parchment paper.
In a saucepan over medium heat, melt the butter and chocolate chips, stirring until smooth. Remove from heat and let cool slightly.
In a mixing bowl, whisk together the sugar and eggs until well combined. Add the vanilla extract and mix.
Gradually add the melted chocolate mixture to the egg mixture, stirring constantly. Sift in the cocoa powder and mix until smooth.
Pour the batter into the prepared pan and smooth the top with a spatula. Bake for 25 minutes, or until the torte is set and a toothpick inserted into the center comes out clean.
Let the torte cool in the pan for 10 minutes, then remove the sides of the pan and let it cool completely on a wire rack. Dust with powdered sugar before serving, if desired.