Preheat your oven to 375°F (190°C) and line a jelly roll pan with parchment paper, lightly greased.

In a large mixing bowl, beat together eggs and granulated sugar until thick and pale, about 5-7 minutes.

Gently fold in the flour, cocoa powder, and salt until just combined, then pour into the prepared pan and bake for 10-12 minutes.

Transfer the cake onto a powdered sugar-dusted towel and roll tightly while still warm, then cool completely.

Whip the heavy cream, powdered sugar, espresso powder, and vanilla until stiff peaks form.

Unroll the cooled sponge and spread the espresso cream evenly, then re-roll seam-side down.

Heat heavy cream until simmering, pour over chopped dark chocolate, stir in butter until smooth for ganache.

Spread the ganache over the rolled cake, dust with powdered sugar, and chill for 30 minutes before serving.