Mix milk with lemon juice and let stand for 10 minutes.
Mix the melted butter, brown sugar, egg yolks, pumpkin puree and the scraped vanilla pulp with the lemon milk. Mix the flour, baking powder and spices and stir into the mixture. Beat egg whites with a pinch of salt until stiff and fold in.
Line a baking sheet with parchment paper, spread the dough on it and bake at 180 degrees top / bottom heat for around 25 minutes, allow to cool.
For the frosting, mix together the cream cheese, melted butter, powdered sugar, honey and scraped vanilla pulp and spread on the cake.