Pancakes with blackberries

200 g white flour
1 tsp sugar
1/4 tsp salt
1 tsp lemon zest
400 ml milk
3 tbsp beer
butter for baking
Filling:
2 egg yolks
3 tsp sugar
1 tsp corn flour
250 ml cream
2 tsp vanilla sugar
100 ml whipping cream
50 g nuts
1-2 tbsp port (optional)
blackberry jam

1. Whisk the egg yolks and the sugar together and whisk the corn flour in. Bring the cream and the vanilla sugar to the boil. Pour the boiling hot cream into the egg yolk mixture while stirring well. Pour the mixture back into the pan and heat while stirring continually, until just before boiling (must not boil). Take pan of the heat and add the chopped nuts.
2. Mix the pancake ingredients and bake the pancakes. Put them on a plate on top of each other to make sure they stay soft.
3. Make sure the custard is cool and fold in the whipped whipping cream and the port if desired.
4. Arrange the cool custard on the hot pancakes and roll together. Serve immediately with blackberry jam.