For the sponge:

• Preheat oven to 180°C/360°F. Grease a Swiss roll pan (I used a 16 x 11 inch pan) with at least a 2cm/3/4 inch lip with oil spray and line base and sides with baking paper.
• Place eggs and sugar in a stand mixer with a whisk attachment and whisk on high speed for 6-8 minutes until thick and pale (the volume will markedly increase towards the end).
• Place coffee and flour in a small bowl and mix together.
• In two batches, sift the flour/coffee mixture over the eggs and gently fold through using a metal spoon. Pour gently into prepared pan and tilt from side to side to even out.
• Bake for 18-20 minutes or until centre of sponge just springs back when pressed (mine only took about 16 minutes). Remove pan from oven and place on a wire rack. NB: Keep the oven on to roast the hazelnuts.
• Lay a clean tea towel over a large board. Invert the hot sponge onto clean tea towel and carefully peel off backing paper. Roll the sponge up (with the tea towel inside) from short edge to form a roulade and set aside to cool completely.

For the filling

• Place ricotta, mascarpone, vanilla and icing sugar in a bowl and whisk until smooth. Place in the fridge until ready to use.

For the hazelnut praline:

TO ROAST THE HAZELNUTS

• Place the 2.4 oz whole hazelnuts on a shallow lipped tray and put into the oven (which is still at 180°C/360°F). Roast for up to 10 minutes, checking and stirring every couple of minutes, to ensure the nuts don’t burn (though the outer skins will burn). When you see evidence of the nuts browning, and they smell fragrant, take them out of the oven. Place them immediately into a clean tea towel and wrap them so that they steam inside the towel. Wait for a few minutes and then, while they’re still wrapped tightly in the tea towel, vigorously rub them together – this will loosen the skins. Unfold the tea towel, pick out the clean hazelnuts (if there are still quite a few with their skins on, repeat the process). Discard the skins carefully (as they tend to get everywhere!).

FOR THE PRALINE

• Place 50g (1.7 oz) of the hazelnuts into a shallow baking tray lined with baking paper (keeping the remaining 20g (0.7 oz) aside for decorating later.
• On a moderately low heat, heat the sugar in a frying pan until melted without stirring (it helps to swirl the pan to ensure even cooking). Once the colour changes to a copper colour (be careful it doesn’t burn!), pour over the nuts. Leave to cool completely.
• Break up the cooled praline into smaller pieces and add to a food processer. Pulse to reduce the praline to a coarse powder. NB: If making ahead store in a sealed container and store in a dry place (don’t place in fridge).

To assemble:

• Unroll the sponge and spread filling evenly over the inside of the roulade using an off-set spatula.
• Scatter the praline powder evenly over the filling (you may have some praline left over, which you can use at another time).
• Carefully roll the sponge back up from the same short end and place on a platter with the seam at the bottom.
• Dust the roll with cocoa using a sieve. Take the hazelnuts reserved for decorating, roughly chop them and scatter over the roulade.