Preheat your oven to 325°F (160°C).
Grease an 8x8-inch baking dish or individual ramekins.
In a large bowl, sift together the cocoa powder, baking powder, and salt.
In another bowl, whisk together the melted butter and granulated sugar until combined.
Add the eggs and vanilla extract to the butter mixture, whisking until just combined.
Gradually add the dry ingredients to the wet mixture, stirring until just combined.
Fold in the semi-sweet chocolate chips gently.
Pour the batter into the prepared baking dish or ramekins and smooth the top.
Bake for 30-35 minutes, until the edges are set but the center is still soft.
Let it cool for about 10 minutes before serving.
Dust with powdered sugar before serving, if desired.
