Chocolate lovers go crazy over the rich, chocolate flavor and tender crumb of this cake. The big bonus is it's easy to make and takes just minutes to mix together. Chocolate is always a hit and this cake is always a crowd-pleaser at potlucks and parties.
Cut butter into pieces and combine the 1 cup butter, 1/3 cup cocoa, and 1 cup water in a small saucepan and heat over low heat. Stir constantly until butter is melted.
Remove the mixture from the heat. Using an electric hand or stand mixer, beat buttermilk, eggs, baking soda, and vanilla extract until smooth.
Gradually add melted butter mixture, beating until mixed.
In a medium bowl, combine sugar, flour, and salt. Add to buttermilk mixture and beat until blended. Pour batter into prepared pan.
Bake for 30 to 35 minutes, or until set in the middle.
Frosting
Combine butter, cocoa, and buttermilk in a medium saucepan. Heat over medium heat, stirring constantly, until mixture is smooth. Remove from heat and stir in powdered sugar, vanilla, and pecans (if adding).
Pour the frosting over cake while the cake is still warm. Allow the frosting to cool and set a bit before slicing.