• Preheat oven to 350F (175C) and thoroughly grease and flour a 10x15 jelly roll pan (or spray with baking spray).
• Combine butter, water, and cocoa powder in a medium-sized saucepan over low heat and cook, stirring occasionally, until the butter is melted. Increase heat to medium and bring to a boil. Remove from heat and allow mixture to cool for 15-20 minutes.
  1 cup (226 g) unsalted butter, 1 cup (235 ml) water, 1/3 cup (33 g) cocoa powder
• While butter/cocoa mixture is cooling, whisk together flour, sugar, baking soda, salt and instant coffee in a large bowl.
  2 cups (250 g) all-purpose flour, 1 ½ cups (300 g) granulated sugar, 1 teaspoon baking soda, 3/4 teaspoon salt, 1/2 teaspoon instant coffee, ½ cup (100 g) light brown sugar, firmly packed
• In another bowl, whisk together sour cream and eggs and vanilla. Stir this into your dry ingredients until combined.
  1/2 cup (125 g) sour cream, 2 large eggs, 1 teaspoon vanilla extract
• Once the chocolate mixture has cooled for at least 15 minutes, stir into your flour/sour cream mixture until mixture is smooth and completely combined.
• Spread batter into prepared jelly roll pan and bake on 350F (175C) for 18-22 minutes or until a toothpick inserted in the center comes out clean or with a few moist crumbs.
• Once cake has finished baking (or several minutes before), begin preparing frosting.

FROSTING

• Combine milk and butter in a medium-sized saucepan and cook over medium/low heat until butter is melted. Once butter has melted, remove from heat and whisk in cocoa powder until combined. Add powdered sugar and vanilla extract and whisk until smooth.
  6 Tablespoons whole milk, 1/2 cup (113 g) salted butter , 6 Tablespoons natural cocoa powder, 4 cups (500 g) powdered sugar, 3/4 teaspoon vanilla extract
• Pour over cake while cake is still warm. If using pecans, sprinkle over frosting now.
  1 cup toasted pecans
• Allow frosting to harden (about one hour) and then slice and serve!