Preheat Oven: Preheat the oven to 325°F. Spray a 9×5-inch metal loaf pan with nonstick cooking spray and set aside. This moderate temperature ensures the brownie bread bakes evenly and develops a fudgy interior without burning.
Melt Chocolate: To a medium microwave-safe bowl, add the milk chocolate chips. Microwave in 30-second intervals, stirring after each, until smooth and melted. Set aside to cool slightly. Allowing the chocolate to cool prevents it from cooking the eggs when added to the mixture.
Combine Dry Ingredients: In a medium bowl, whisk together the flour, cocoa powder, baking soda, and kosher salt. Whisking ensures even distribution of the leavening agent and removes any lumps in the cocoa powder for a smooth texture.
Mix Wet Ingredients: In the bowl of a stand mixer fitted with a paddle attachment, add the eggs and granulated sugar. Beat on medium-high speed until the mixture is light and fluffy, about 5 minutes. This step incorporates air into the batter, which helps create the proper texture.
Combine Wet Mixture: Reduce the mixer speed to low. Add the melted chocolate, vegetable oil, and water. Mix until fully combined and smooth. The low speed prevents splashing and ensures thorough incorporation.
Add Dry to Wet: Gradually add the dry ingredients to the wet mixture, mixing just until no lumps remain. Overmixing can develop too much gluten, resulting in a tough bread, so mix only until combined.
Add Mint Chips: Remove the bowl from the mixer. Fold in 1 cup of Andes Crème de Menthe baking chips. Reserve the rest of the baking chips for the topping. Folding by hand ensures the chips are evenly distributed without being broken.
Fill Pan: Pour the batter into the prepared loaf pan and smooth the top. Smoothing ensures even baking and a nice presentation.
Bake: Bake for 85-90 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs but no wet batter. The long baking time is necessary for this dense, moist bread to cook through completely.
Cool and Top: Allow the bread to cool in the pan for about 15 minutes, then transfer to a wire rack. While the bread is still slightly warm, melt the remaining Andes chips in a microwave-safe bowl in 30-second intervals, stirring between each, until smooth. Spread or drizzle the melted chips over the top of the loaf. Let the topping set as the bread cools completely.