In a bowl, whisk together all the crepe ingredients until smooth. You could use a blender. Rest the batter for about 30 mins in the fridge.
Place a crepes skillet on a medium heat and lightly brush with vegetable oil or melted butter.
Pour in about ¼ cup (60 ml) of batter, tilting and swirling the skillet until it coats the bottom evenly. Cook for 30-40 seconds then flip and cook for another 30-40 seconds on the other side.
Repeat until you have used up all the batter. You should end up with around 30-35 crepes.
For the mascarpone frosting:
Cream together the mascarpone, honey, and vanilla.
Set aside until assembly.
For the hazelnut brittle:
Line a baking tray with parchment paper and brush with vegetable oil. Roughly chop the hazelnuts.
Place the sugar into a medium saucepan on low-medium heat and melt until caramelized, mixing constantly. Mix in the hazelnuts and pour onto the prepared stray. Spread it evenly and let cool completely. Move fast as this mix hardens quickly.
Assembly:
To assemble the cake, place one crepe on the serving platter. Spread with 2-3 tablespoons of berry jam leaving 1/2 cm (1/5 inch) border.
Top with another crepe and spread that one with 2-3 tablespoons of mascarpone frosting, again leaving 1/2 cm (1/5 inch) border.
Continue alternating fillings until you have used all your crepes. Don't put a filling on the top crepe. Keep aside 2-3 tablespoons of mascarpone frosting for final assembly.
If you end up with a crepe cake with a dome like shape, gently press in the center to flatten it. Wrap the cake in cling film and refrigerate for at least 4 hours.
Once the crepe cake is out of the fridge, spread on top the remaining mascarpone frosting and decorate with fresh berries and roughly chopped hazelnut brittle.
Notes
You could replace the berry jam and hazelnut brittle with other variations for different seasons or themes. The below combinations are just as delicious: