Make the Sponge:

1. Preheat Oven: Preheat your oven to 180°C (350°F) and line a 10×15-inch Swiss roll pan with parchment paper. Grease the paper lightly.
2. Beat Egg Yolks and Sugar: In a mixing bowl, whisk the egg yolks with half the sugar until pale and thick, about 3-4 minutes. Stir in the vanilla extract.
3. Whip Egg Whites: In a clean bowl, beat the egg whites with a pinch of salt until soft peaks form. Gradually add the remaining sugar and beat until stiff peaks form.
4. Combine and Fold: Gently fold the whipped egg whites into the yolk mixture in batches, taking care not to deflate the batter.
5. Add Dry Ingredients: Sift the flour and cocoa powder over the batter and gently fold until just combined.
6. Bake: Spread the batter evenly into the prepared pan and bake for 10-12 minutes, or until the sponge is set and springs back when touched.

Roll the Sponge:

7. Cool in a Towel: While the sponge is still warm, invert it onto a clean kitchen towel dusted with powdered sugar. Carefully peel off the parchment paper, then roll the sponge up tightly with the towel. Let it cool completely in the rolled shape.

Prepare the Baileys Cream Filling:

8. Whip the Cream: In a chilled bowl, whip the heavy cream with powdered sugar, vanilla extract, and Baileys until soft peaks form. Be careful not to overwhip.

Assemble the Roulade:

9. Unroll the Sponge: Gently unroll the cooled sponge. Spread an even layer of Baileys cream over the surface, leaving a small border around the edges.
10. Roll It Back Up: Carefully roll the sponge back up, using the towel to guide you. Place seam-side down on a serving platter.

Chill and Decorate:

11. Chill the Roulade: Wrap the roulade in plastic wrap and refrigerate for at least 2 hours to set.
12. Dust and Garnish: Dust with cocoa powder or powdered sugar before serving. Add chocolate shavings or curls for extra flair.