Preheat oven to 350°F.  Coat a 9x5-inch loaf pan with non-stick oil spray and line with a long strip of parchment paper with ends of paper extended.  Coat parchment paper with oil spray.

In a large bowl, whisk together the oil, sugar and milk.  Stir in the eggs, vanilla and mint extract, add the sour cream and stir until just combined.

In a separate bowl, add the flour cocoa powder, baking soda and salt, whisk together.  Fold the flour mixture into the wet mixture just until combined.  Stir in the chocolate chips.

Pour the batter into the prepared loaf pan and bake for 45-50 minutes until a cake tester or toothpick inserted into the thickest part of the cake comes out with a few crumbs.

Transfer from the oven and set on a wire cooling rack.  When cool, use the parchment paper overhang ends to lift the cake from the pan.