Preheat the oven to 350°F (175°C). Grease a 9 × 5-inch loaf pan with nonstick cooking spray or butter. For easier removal, line the bottom and long sides with parchment paper, leaving a little overhang.

In a medium mixing bowl, combine the brownie mix, hot fudge sauce, eggs, and vegetable oil.

Stir gently with a whisk or spatula until all the ingredients are thoroughly combined and no dry brownie mix remains. The batter should be thick, smooth, and chocolatey. Avoid overmixing.

Pour the prepared batter into the greased loaf pan and spread it evenly with a spatula. Fill the pan no more than three-quarters full. If there is extra batter, bake it separately in a greased muffin pan.

Place the loaf pan on the center rack of the preheated oven and bake for approximately 45 minutes. Check for doneness, then continue baking for another 15 minutes or longer if needed.

Insert a toothpick into the center of the loaf. It should come out with moist crumbs but no liquid batter. If the top begins to brown too quickly, loosely cover it with aluminum foil while the center finishes baking.

Remove the brownie bread from the oven and place the loaf pan on a wire rack. Allow it to cool completely for approximately 1 hour before removing it from the pan.

Carefully lift the cooled loaf out using the parchment paper or run a thin knife around the edges to loosen it.

Slice the Hot Fudge Brownie Bread into 10 portions and serve. Enjoy on its own or with a scoop of vanilla ice cream and an extra drizzle of warm fudge sauce.