Step 1: Prepare the Brownie Bread Batter

Preheat your oven to 350°F (175°C). Grease a 9x5-inch loaf pan and line it with parchment paper. In a medium bowl, whisk together flour, cocoa powder, baking powder, and salt. In a large bowl, mix melted butter, granulated sugar, and brown sugar until combined. Add the eggs one at a time, followed by the vanilla extract. Gradually add the dry ingredients to the wet ingredients, alternating with the milk, and mix until just combined.

Step 2: Make the Hot Fudge Sauce

In a saucepan, heat the heavy cream and sugar over medium heat until it begins to simmer. Remove from heat and stir in the chocolate chips and vanilla extract until smooth and glossy.

Step 3: Assemble and Bake

Pour half of the brownie bread batter into the prepared loaf pan. Drizzle half of the hot fudge sauce over the batter. Add the remaining batter on top, followed by the rest of the hot fudge sauce. Use a knife or skewer to swirl the layers together. Bake for 45-50 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs.

Step 4: Cool and Serve

Let the bread cool in the pan for 15 minutes, then transfer it to a wire rack to cool completely. Dust with powdered sugar and serve with fresh berries if desired.