Preheat your oven to 350°F (175°C) and line a jelly roll pan (15x10 inches) with parchment paper, allowing some overhang for easy removal. Ensure your eggs are at room temperature to help create a fluffier sponge in your Classic Yule Log.

In a mixing bowl, sift together the all-purpose flour, cocoa powder, baking powder, and salt. In a separate bowl, beat the egg yolks with half of the granulated sugar until pale and thick, around 5 minutes. Gently fold the dry ingredients into the egg mixture until just combined.

Using a clean, dry bowl, whip the egg whites until soft peaks form. Gradually add the remaining granulated sugar and continue to beat until stiff peaks form, about 3-5 minutes.

Gently fold the whipped egg whites into the chocolate batter in three additions until no more white streaks are visible.

Spread the batter evenly into the prepared jelly roll pan, smoothing the surface. Bake for about 12-15 minutes until set and springs back when lightly pressed.

Immediately after baking, dust a kitchen towel with powdered sugar, invert the cake onto the towel, and roll it up with the towel from one short end to the other. Allow to cool completely wrapped.

In a chilled mixing bowl, whip the heavy cream with the powdered sugar and vanilla until stiff peaks form, about 3-4 minutes.

Unroll the cooled cake and spread the whipped cream filling evenly over the surface. Roll the cake back up tightly creating a log shape. Wrap in plastic wrap and refrigerate for at least 30 minutes.

In a mixing bowl, beat the softened butter until creamy, then gradually add powdered sugar and cocoa powder. Mix in milk or cream until smooth and spreadable.

Unwrap the chilled cake and place it seam-side down on a platter. Frost the entire log generously with the chocolate buttercream, creating a bark-like texture.

Finish by dusting the frosted Yule Log with powdered sugar and garnish with fresh cranberries, rosemary, or edible glitter. Serve with warm drinks.