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.

While butter/cocoa mixture is cooling, whisk together flour, sugar, baking soda, salt and instant coffee in a large bowl.

In another bowl, whisk together sour cream and eggs and vanilla. Stir this into your dry ingredients until combined.

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.

FROSTINGCombine 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.

Pour over cake while cake is still warm. If using pecans, sprinkle over frosting now.

Allow frosting to harden (about one hour) and then slice and serve!