Yule Log

There were surprisingly not many recipes to be found on this. And most of them have coffee in it and I think that is what is so different about the Yule Log. But here is the original I found. Mine definitely wasn't as pretty as the one in the picture but it was pretty good. And it did take some time to make.
A quick definition of the Yule Log:
A Yule log is a large wooden log which is burned in the hearth as a part of traditional Yule or Christmas celebrations in several European cultures. It can be a part of the Winter Solstice festival or the Twelve Days of Christmas, Christmas Eve, Christmas Day, or Twelfth Night.
The expression "Yule log" has also come to refer to log-shaped Christmas cakes, also known as "chocolate logs."

So anyway. I had to alter the mocha butter cream frosting part. There is a lot of butter and without the coffee I think it would have been okay to omit some of the butter.  So here's my version of the recipe.

Yule Log
5 eggs, room temperature, separated
2/3 cup sugar
2T flour
3T unsweetened cocoa
FILLING:
2 1/2T flour
1/2 cup milk
1/2 cup sugar
1/2 cup butter
1/2 t vanilla extract
BUTTER CREAM FROSTING:
1/2 cup butter
1/2 cup confectioners' sugar
1T unsweeted cocoa

1. In a large mixing bowl, beat egg yolks at high speed until light and fluffy. Gradually add sugar, beating until mixture is thick and light-colored. Add flour and cocoa, beating on low speed. 
2. In another bowl, beat egg whites until soft peaks form; fold into batter. mix until no streaks of white remaining. 
3. Grease a 15-in. x 10-in. x 1-in. pan; line with waxed paper(a MUST!), and grease and flour paper (LOTS!). Spread batter evenly in pan. 
4. Bake at 350 degrees F for 15 minutes or until cake springs back when touched lightly. Cool completely on wire rack. 
5. Remove paper; roll cake onto an 18-in. long piece of waxed paper (or damp towel) dusted with confectioners' sugar. Trim edges from all four sides of cake.
FILLING: Combine flour and milk in a saucepan. Cook over low heat; stirring until thick. Cool. In a mixing bowl, cream sugar, butter and vanilla. Add flour mixture; bet until fluffy. Fold in walnuts if desired. Spread on cake; roll up, jelly-roll style, starting from one short end.
FROSTING: Beat butter until fluffy in a small bowl. Beat in sugar and cocoa. Spread over cake, using a fork to create a bark-like effect. Sprinkle with confectioners' sugar and nuts if desired.