In a bowl stir yeast into warm water to soften. In a second mixing bowl beat the 1/4 cup butter, sugar, and salt until creamy. Add 1/2 cup of the flour, the cardamom, and milk. Add the egg and egg yolk. Add softened yeast; beat until well combined. Stir in remaining flour and the raisins until smooth and dough comes together. Cover bowl; let rise in a warm place until double (about 2 hours). Refrigerate dough 6 hours. (Or omit 2-hour rising time and refrigerate dough 12 to 24 hours.)
Grease a baking sheet; set aside. Turn dough out onto a well-floured surface.
Roll dough into a 15x10-inch rectangle. Place half the butter slices evenly on dough; lightly press butter into dough. Fold dough crosswise into thirds. Rotate dough a quarter turn to the right. Repeat rolling and folding using remaining butter slices. Roll again to 15x10-inch rectangle; fold crosswise into thirds. Give dough a quarter turn to the right.
Roll folded dough into a 12x9-inch rectangle. Cut dough into twelve 3-inch squares. Fold corners of square into center, pressing lightly to seal. Place each on prepared baking sheet. Using the rounded side of a floured tablespoon, press firmly to make an indentation in the center of each dough square. Cover; let rise in a warm place until double (45 to 55 minutes). (You may see the butter slices soften and begin to melt out of rolls.) Press indentation again, if necessary.
Bake in a 375 degree F oven for 10 to 12 minutes or until golden brown. Remove from pan. Brush with melted butter; cool on wire racks. Meanwhile, prepare Cream Filling and Powdered Sugar Icing. Spoon cream filling into the center of each Danish. Drizzle each with icing. Makes 12 Danish.
Powdered Sugar Icing
In a small bowl, combine powdered sugar, vanilla, and 1 tablespoon milk. Stir in additional milk, 1 teaspoon at a time, until icing reaches drizzling consistency.
In a medium saucepan combine milk and flour using a whisk. Cook and stir over medium heat until thickened and bubbly. Reduce heat; cook and stir 2 minutes more. Remove from heat. Cover surface with plastic wrap. Cool to room temperature (do not stir). In a mixing bowl beat butter, sugar, and vanilla with an electric mixer on medium speed until light and fluffy. Add half the cooled cooked mixture at a time, beating on low speed after each addition until smooth. Makes about 1-1/2 cups.