Step 1

In a small bowl, mix together the mascarpone and cream cheese until smooth.

Step 2

Position an oven rack in the middle of the oven and preheat the oven to 350°F. Grease and flour a 12 cup Bundt pan.

Step 3

In a medium bowl, mix together the flour, baking powder, and baking soda.

Step 4

In the bowl of a stand mixer fitted with a paddle, beat the butter on medium speed until creamy. Add the granulated sugar and salt, and beat until light and fluffy, 4 to 6 minutes. Add the eggs one at a time, beating well after each addition, stopping to scrape down the sides of the bowl as needed. Add the vanilla and mix on low speed to combine. Add one-third of the flour mixture and mix on low speed to combine. Add half of the buttermilk and mix on low speed to combine. Add half the remaining flour and then the remaining buttermilk, beating on low speed after each addition to incorporate. Add the remaining flour and mix on low speed until just combined. Use a spatula to give the batter a couple of turns to make sure it is fully mixed. Remove ½ cup (110 g) of the batter and mix it with the mascarpone mixture.

Step 5

Pour one-third of the batter into the prepared pan. Dollop half of the mascarpone mixture over the top of the batter and sprinkle with half of the mini chocolate chips. Pour half of the remaining batter over the top, repeat with the remaining mascarpone and mini chocolate chips, and cover with the remaining batter. Drag a knife through the batter, making a figure-eight motion, around the whole Bundt one time. Tap the pan twice on the counter to release any air bubbles. Bake the cake until a wooden skewer or toothpick inserted into the center comes out with the slightest bit of crumb, 65 to 80 minutes.

Step 6

While the cake is baking, in a small saucepan, combine the espresso, granulated sugar, and salt. Heat over medium heat until the sugar is dissolved, 3 to 4 minutes.

Step 7

Transfer the cake pan to a wire rack and let cool for 10 minutes. Invert the cake onto the rack and let cool for 15 minutes.

Step 8

Using a pastry brush, brush the coffee soak over the entirety of the cake, using all of the mixture (this will take a few minutes). Let the cake cool completely. Wrap the cake in plastic wrap and chill in the refrigerator overnight.

Step 9

When ready to serve, dust the top of the cake with cocoa powder. The cake can be wrapped in plastic wrap and refrigerated for up to 3 days.