Preheat oven to 375 degrees
Line a baking tray with parchment paper.
Add the rolled oats to a high speed blender or food processor and blend until the oats resemble a flour-like consistency.
Then, grab a large bowl. Crack the eggs, adding the egg yolks and the egg whites into the large bowl.
Also, add the vanilla extract and sugar to the bowl.
Then, using a handheld electric mixer or stand mixer, blend the eggs, sugar, and vanilla extract for 10 minutes, until the mixture has almost doubled in quantity.
Using a spatula, fold the dry ingredients (the blended oats, cocoa powder, and salt) into the egg, sugar, and vanilla mixture.
When this is well-mixed, pour this oat chocolate yule log batter into the parchment-lined baking tray.
Bake for 9 minutes.
Remove this from the oven, and, immediately, cover the baking tray with foil. I like to fold the foil over the sides of the baking tray with a kitchen towel and I usually just leave the kitchen towel over the foil. Let this cake cool down completely.
When the cake is cool, make some strong coffee. Then, remove the towel and foil from the baking tray and brush with the coffee, and make the filling.