1Take a bit of the milk and dilute the yeast in a small bowl.
2Combine the white flour, whole wheat flour, salt, sugar, melted butter, and dissolved yeast in the bowl of a stand mixer. Attach the dough hook and knead for 7 minutes to get a nice, smooth dough.
3Cover the bowl with a damp cloth and let the dough rise for 30 minutes in a warm place. This is a fairly dense dough and will rise less than a bread dough.
4On a floured surface, roll out the dough and divide it in two. Sprinkled the chopped chocolate over the first half. Shape it into a ball. Sprinkle the crushed pralines over the second half and shape it into a ball. Then divide each ball of dough into 5 small balls. Flatten each ball with the palm of your hand, then pull and tuck the four corners into the center and turn the dough over to form a bun.
5Preheat oven to 430F.
6Place the buns on a baking sheet lined with a silicone baking mat or piece of parchment paper and let them rise for 40 minutes.
7Beat the egg in a small bowl. Brush each morgenboller with some egg wash and sprinkle with slivered almonds or hazelnuts (optional). Bake for 10 to 12 minutes.
8Remove the buns from the oven. Wait a few minutes before tasting them because the chocolate and pralines will be hot.