Espresso Marbled Loaf Cake

Preheat the oven to 350°F / 175°C. Butter and line a 1 lb (8x4) loaf pan with parchment paper.
In a medium-sized bowl, whisk together the flour, baking powder, and salt. Set aside.
In the bowl of a stand mixer fitted with the paddle attachment, or with a hand mixer, beat together the butter, oil, and sugar for 5 minutes until light and fluffy.
Scrape down the sides of the bowl, and add in one egg at a time, beating until well combined. Add in the vanilla with the second egg.
Alternate between adding the flour mixture and the milk and sour cream. Fold in ½ of the flour mixture, then all of the milk and sour cream, followed by the rest of the flour mixture.
Brew the espresso. In a small bowl, whisk together 18g (3 tbsp.) of cocoa with 40g (1 ⅓ oz.) of the espresso. In another small bowl, whisk together 6g (1 tbsp.) of cocoa with the remaining espresso.
To the bowl with more cocoa, add in 1 c. of batter. To the bowl with less cocoa, add in 1 ⅓ c. of batter. Mix each bowl just until no streaks remain.
Alternate scooping in the three different batters into the loaf pan. Once all the batter has been used, use a knife to gently swirl the batters together.
Bake for 40-50 minutse, or until a knife inserted in the middle of the cake comes out with just a few moist crumbs.
While the cake is cooling, make the espresso ganache.

Place the chocolate into a small mixing bowl and set aside.
Transfer the espresso beans to a sealed plastic bag, and lightly crush them.
Add the crushed espresso beans and the heavy whipping cream to a small saucepan. Set the mixture over medium heat and bring it to a simmer.
Once the mixture is simmering, turn off the heat and allow the mixture to sit for at least 5 minutes, and up to 20 minutes.
Once the cream has sat for 5 minutes, put it back on medium heat and once again bring it to a simmer.
Once simmering, pour the cream through a fine-mesh sieve over the chocolate.
Cover the bowl with a lid or plate. Let the mixture sit for 1 minutes, then whisk the ingredients together until you have a smooth ganache.
Pour the ganache over the cake once the cake has cooled to room temperature. Or, if you'd like a whipped ganache, allow the ganache to cool in the fridge and then whip it up with a hand or stand mixer before spreading it on the cake. Slice, serve, and enjoy!