Made 2/21 for Coles birthday. Great! My new favorite

Preheat oven to 325 F. For cake, line 13 by 9 pan with nonstick spray, line with parchment and spray with nonstick spray.

Combine sugar, flours, baking soda and salt in mixing bowl.

In 4-cup measuring cup, whisk boiling water and cocoa powder. Set aside.

In a 2-cup measuring cup, whisk sour cream, eggs and egg yolks, then whisk in oil,. Whisk into cocoa and water mixture.

On low speed, add liquid to the dry mixture for 30 seconds just until the batter is smooth.

For cake, pour the batter into the prepared pan and bake until the cake springs back when pressed and reaches an internal temperature of 205 degrees F, 30 to 35 minutes. Cool for 30 minutes then remove.

For cupcakes, use #16 disher (flat, no more) to fill cupcake papers 2/3. Bake 15 mins to 205 F.