To prepare a zwetschekuchen German plum tart recipe, you will first need to gather your ingredients. You will need the following ingredients: Preheat the oven to 375?F (190?C) Grease and flour two 9-inch tart pans and set aside. In another large mixing bowl, combine the flour, baking powder, sugar, and salt. Gradually add the dry ingredients to the wet ingredients, mixing well after each addition. Pour the mixture into the prepared tart shells. Bake the tarts for 20 to 25 minutes, or until the tops are golden brown. Allow to cool before serving.