Scrape the seeds from the vanilla pod, and reserve the pod (you will need it later!). Mix the flour with the salt, sugar, and vanilla pulp in a large bowl. Form a small well in the middle of the flour mixture.
Dissolve the yeast in 3 tablespoons of milk and pour the mixture carefully into the well. Cover with a clean kitchen towel and let rise in a warm place for 15-20 minutes.
Cut about 5 tablespoons of the butter into small cubes, and scatter over the top of the flour mixture. Add the egg and half of the milk, and knead together to form a soft dough. This can also be done with a food processor or standing mixer with the dough hook attachment. Cover again and let rise for about 1 hour, or until it has doubled in size.
Knead the dough again, then form twelve balls of equal size. Place them onto a floured countertop and cover with the kitchen towel for 30 minutes.
Pour the remaining milk into a Dutch oven, and add the butter, the vanilla pod, and the maple syrup. Place over low heat and gently warm it up so that the butter starts to melt, then take it off the stove.
Place the dough balls into the pot in a single layer so they are touching. Place the back on the stove and cover tightly. Bring just to a boil over high heat, then turn the heat down to low immediately.
Let the dumplings steam for about 30 minutes. It is really important that you do not open the lid, or they won’t become fluffy on top and caramelized on the bottom.
Here’s how you’ll know that the dish is ready: At first you might hear something like a singing, chirping sound as the dumplings start to crackle in the pot. This means the liquid has evaporated and the dumplings have formed a nice crust.
Take the pot off the stove and let it sit off the heat for about 5 minutes, with the lid still in place.
Take out your dumplings and serve while they are still hot, with homemade vanilla sauce.