Preheat oven to 350°F (175°C) and line a jelly roll pan with parchment paper.

Beat egg whites until soft peaks form. Gradually add ¼ cup sugar and beat until stiff peaks form.

In another bowl, beat egg yolks with the remaining ¼ cup sugar until pale and thick. Stir in vanilla.

Sift flour, cocoa powder, baking powder, and salt, then gently fold into yolk mixture.

Fold egg whites into the batter carefully to keep the volume.

Spread batter in the prepared pan. Bake for 10–12 minutes, or until the cake springs back when lightly touched.

While warm, roll cake up in a powdered sugar-dusted towel starting from the short end. Let it cool completely rolled up.

Whip heavy cream with powdered sugar and vanilla until stiff peaks form.

Carefully unroll the cake, spread whipped cream evenly, and gently roll it back up. Wrap in plastic and refrigerate for 1 hour.

Prepare buttercream by beating butter, powdered sugar, cocoa powder, milk, and vanilla until fluffy.

Unwrap the cake, frost with buttercream, and create bark-like texture using a fork.

Decorate with cranberries, greenery, and a dusting of powdered sugar before serving.