First, make the tiramisu pancake filling: in a large bowl using an electric whisk, whisk together the mascarpone, egg yolks and sugar until smooth and creamy. Pour in the double cream and Baileys (if using) and whisk again until thickened like whipped cream - take care not to overwhisk. Set aside.
Next, make the pancakes: sift the plain flour into a large mixing bowl. Add the sugar, egg, egg yolk, melted butter and milk. Whisk well until combined to form a smooth batter with no lumps.
To cook the pancakes: place a medium-sized pancake pan over a medium-high heat. Add a small knob of butter and carefully swirl to cover the base. Wipe out any excess with a piece of kitchen paper.
Ladle in enough batter to cover the base of the pan in a thin layer when you gently swirl it - it should be equivalent to a few tablespoons. You don’t want the pancake to be too thick - we are going for delicate crêpe-style pancakes here. Cook for about 30 seconds to 1 minute, or until golden underneath, without touching it. Then use a palette knife or spatula to loosen the edges and gently turn over the pancake. Of course, if you are feeling brave, you can attempt a flip!
Continue to cook for about 30 seconds on the other side - or until golden underneath. Slide onto a plate and repeat until you have used up all your batter. Place a piece of non-stick baking paper between each pancake to stop them sticking.
Next, if dunking the pancakes in the coffee-liqueur, mix together the cooled espresso and Baileys in a shallow dish.
One pancake at a time, briefly dip into the coffee-liqueur mix. This literally only needs a few seconds - just like when dipping ladyfingers for tiramisu. Place onto a flat plate and spread with the mascarpone filling.
Fold or roll the pancakes, dust with cocoa powder and enjoy!