Preheat your oven to 350°F (175°C). Grease a loaf pan with butter or non-stick spray and dust with flour.

In a medium bowl, whisk together flour, sugar, cocoa powder, baking soda, baking powder, and salt. Set aside.

Cream the butter until smooth, then add the sour cream, eggs, and vanilla, mixing until creamy.

Gradually add dry ingredients to the wet mixture, stirring gently until just combined. Fold in chocolate chips if using.

Pour batter into the prepared loaf pan, smoothing the top. Fill the pan to about two-thirds full.

Bake for 50 minutes until the top springs back and a toothpick comes out clean.

Let the cake cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.