For the dough, mix vanilla pulp with milk. Add yeast and melt by mixing with a fork. Then add flour, eggs, sugar, salt and butter cut into pieces. Knead with a dough hook in the mixer for about 2 minutes to get a rather homogenous dough. Increase to medium speed and knead for another 10 minutes. Put the dough in a bowl and cover with cling film. Let first rest at room temperature for some 90 minutes and then in the fridge for an hour.