Preheat your oven to 350°F (175°C) and grease a 9x5-inch loaf pan.
In a large mixing bowl, cream the softened butter and granulated sugar together until light and fluffy.
Add the eggs one at a time, mixing well after each addition.
In another bowl, whisk together the flour, baking powder, and salt. Gradually add this mixture to the butter mixture, alternating with the brewed coffee. Mix until just combined.
Divide the batter into two equal portions. In one portion, stir in the cocoa powder, espresso powder, and vanilla extract.
To create the swirl, alternate spooning the two batters into the prepared loaf pan. Start with a layer of vanilla batter, then add a layer of chocolate batter, and repeat until both batters are used up. Use a knife to gently swirl the two batters together for a marbled effect.
Bake in the preheated oven for 50-60 minutes or until a toothpick inserted into the center comes out clean. Let the cake cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.
For the glaze, whisk the powdered sugar and milk together until smooth. Drizzle over the cooled pound cake before serving.
Notes
Slice the cake and arrange on a serving platter. Drizzle with extra coffee glaze and serve with a cup of coffee on the side for a delightful pairing.