1. Mix the first 4 ingredients in the bowl of an electric mixer fitted with the dough hook. Add the milk. Mix on medium speed. One at a time, add 3 of the eggs. Add the butter 1 tbsp at a time, letting it incorporate before adding more. Knead the dough for about 8 minutes. Cover with plastic wrap and let stand in a warm place until doubled. Deflate the dough and refrigerate, covered, overnight.

2. Butter the molds. Knead the dough; divide into 12 pieces, and cut a quarter off each. Form 12 large and 12 small balls. Place a large ball in a mold. Make a hole in the center with a floured wooden spoon handle. Fit a small ball in the hole. Repeat with the other balls.

3. Cover and let stand in a warm place about 2 hours. Preheat the oven to 375°F (190°C). Lightly brush with the remaining beaten egg. Bake for 15-20 minutes. Let cool on a wire rack.