Preheat oven to 325°F. Line a 9x5-inch loaf pan with parchment paper, letting it hang over the long sides and lightly grease the short ends.

Sift flour, baking powder, and salt into a large bowl.

Cream the butter and sugar in a separate large bowl until very light and fluffy, about 3-5 minutes, using an electric mixer. Scrape the sides, and add the eggs one at at time. Beat for 1 minute in between each egg on medium speed. Add the vanilla.

Slowly add the flour mixture in three parts and mix until just incorporated. It is best to fold in the last bit of flour by hand. Fold in chopped dark chocolate.

Scrape the batter evenly into the prepared pan and smooth out the surface. Bake for 50 to 55 minutes. Check on it after 30 minutes and loosely tent some foil over top if it is browning too quickly. The cake is done when a skewer inserted into the center comes out clean. Transfer pan to a wire rack and let cool in the pan before turning out.

To make the ganache, place cream and corn syrup in a small saucepan and bring just to a boil over medium heat. Once it just comes to a boil, remove from heat and add chopped chocolate. Let stand for 2 minutes and then stir until smooth and glossy. Pour ganache into a clean bowl and let cool at room temperature until thick enough to spread. You can speed this up in the refrigerator, but check on it every 5 or 10 minutes and give it a gentle stir, otherwise it will set completely and be difficult to spread.Spread ganache over cake and serve! Store in an airtight container for up to 3 days.