Directions

1. Heat 1 1/2 cup milk until it's lukewarm in the microwave. In the bowl of an electric mixer with hook attachment add yeast and dissolve then add 1/2 cup sugar, baking powder, vanilla, cardamom and 2/3 of the flour.
   
2. Mix the dough together on low, slowly adding the rest of the flour. You might need a bit more or less flour to form dough that isn't too sticky to knead. When the dough forms a nice ball, add 7 tablespoons softened butter and continue to knead the dough for about ten minutes. Cover and let rise until doubled in size, about one and a half hour.
   
3. Heat 2 cups milk and 1/4 cup of the sugar in a saucepan. Split open the vanilla bean with a knife and carefully scrape out the seeds and add them to the milk. Mix together 1/4 cup sugar and 2 1/2 tablespoons flour and cornstarch in a bowl. Add the egg yolks and 1 egg and whisk together until smooth.
   
4. Once the milk mixture starts to bubble pour about half of it into the bowl with the egg mixture, whisking quickly the entire time. Then return the saucepan to the heat and pour the egg and milk mixture from the bowl back into the saucepan, whisking the whole time. Let the custard cook for 2 minutes, whisking the entire time. By the end it should be quite thick and harder to whisk. After 2 minutes remove the custard from the heat and pour into a clean bowl. Cover with plastic wrap, placing it directly touching the top of the custard. Let the custard cool while the dough finishes rising.
   
5. After the dough has risen, turn it out onto your counter and roll into a long cylinder. Cut it into about 12 even slices. Roll each slice into a round ball and place them all on baking sheets lined with parchment paper. Make sure to leave plenty of space between the buns, as they'll grow in the oven.
   
6. Flatten each ball a bit and then use a 1/4 cup measuring cup to press down a good well in each bun. Be sure to press the dough all the way down and make a bigger well than you'll actually need, as the dough will puff back up a bit in the oven.
   
7. Place vanilla custard in the well of each bun (about 1 – 2 tbsp of custard). Cover with plastic wrap and let rise again for 30 minutes.
   
8. Preheat oven to 410°F. Whisk 1 egg and gently brush each bun with egg wash. Bake for about 10 – 14 minutes in the middle of the oven, until golden brown.
   
9. Sift powdered sugar on top of each of the buns and place on a cooling rack to cool for 10 minutes then serve.