Step 1

Preheat the oven to 325°F (160°C). Grease and line a 9x5-inch loaf pan with parchment paper, leaving a slight overhang on the long sides.

Step 2

In a microwave-safe bowl, warm 1 cup of chocolate chips with the butter in 30-second increments, stirring between each spin, until smooth. Set aside to cool.

Step 3

In a large bowl, sift the flour, cocoa powder, salt, baking powder, and baking soda. Set aside.

Step 4

In a separate bowl, whisk the eggs with the sugars until well combined and light in color. Add the buttermilk, vanilla, and cooled melted butter and chocolate mixture. Whisk until blended.

Step 5

If using, dissolve the espresso powder in the hot water. Add the hot water to the wet ingredients and stir to combine.

Step 6

Add the flour to the wet ingredients and stir gently with a spatula until about halfway combined. Add 1/2 cup of chocolate chips and stir gently until just combined.

Step 7

Pour the batter into the prepared pan and smooth the top. Bake for 50-60 minutes, until a toothpick inserted into the center comes out with a few moist crumbs.

Step 8

Remove the pan from the oven and immediately sprinkle the remaining 1/2 cup of chocolate chips evenly over the surface. Cool in the pan for 10-15 minutes, then transfer to a wire rack to cool.

Step 9

Use a sharp knife to cut the brownie bread into thick slices. Enjoy warm or at room temperature.