Grease and line a 9×5" loaf pan with parchment, leaving overhang on the long sides. Preheat oven to 325°F (163°C).

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

In another bowl, whisk together the sour cream, buttermilk, and vanilla until smooth. Set aside.

In a stand mixer fitted with the paddle attachment (or using a hand mixer), beat the butter, oil, and sugar on medium-high speed for 4 minutes, until light and fluffy.

Add the eggs one at a time, mixing 20–30 seconds after each addition. Scrape down the bowl as needed.

With the mixer on low speed, alternate adding the dry and wet ingredients in three additions, beginning and ending with the dry. Mix just until everything is incorporated.

In a small bowl, whisk together the cocoa powder, espresso powder, and hot coffee into a smooth paste.

Divide the batter in half. Mix the mocha paste into one half, stirring until fully incorporated with no streaks.

In the prepared pan, alternate spoonfuls of vanilla and mocha batter in a checkerboard-style pattern. Once all the batter is added, swirl with a knife or offset spatula in a figure-eight motion.

Bake for 60-70 minutes, or until a toothpick inserted into the center comes out clean.

Cool in the pan for 15 minutes, then transfer to a wire rack to cool completely, about 1 hour.

Place the chopped chocolate in a medium heatproof bowl. In a small saucepan, whisk together the heavy cream, espresso powder, and a pinch of salt. Heat over medium until steaming but not boiling.

Pour the hot cream over the chocolate. Let sit undisturbed for 2 minutes, then gently stir until smooth and glossy.

Pour over the cooled loaf. Let the ganache set slightly before slicing and serving.