Separate one of the duck eggs. Cover the yolk and refrigerate until needed. Whisk the white with the remaining two eggs. Set aside.
Heat the pineapple juice and butter milk until warm to the touch but not hot – 110 degrees. Stir in the yeast and 1 teaspoon sugar. Let sit until foamy, about 5 minutes.
In the bowl of an electric mixer fitted with the paddle attachment, combine the flour, remaining 6 tablespoons sugar, and salt. Mix on low to combine. Add the yeast mixture followed by the duck eggs with the extra white, followed by the melted butter and finally the vanilla. Gradually increase the speed to high and let run for 10 minutes. The dough should be smooth and a little sticky.
Dust a work surface with some flour, scrape out the dough and knead a few times until no longer sticky. Spray a clean bowl with cooking spray, shape the dough into a ball, add to the bowl, turn a few times to coat, and cover with a towel or plastic wrap. Let sit in a draft free place until doubled in size, 2½ hours.
Spray a 9 by 12 baking dish with cooking spray.
Punch the dough down, place on work surface, cut into 15 equal sized pieces and roll into balls with slightly damp hands. Place in the baking pan, 3 across and 5 down. Cover with a cloth or plastic wrap and let rise again for 1 hour or until almost doubled in size. To bake later, cover the pan with plastic wrap and refrigerate before letting rise. Remove from refrigerator, keep covered and let rise for 1 hour and 15 minutes.
Preheat oven to 350 degrees. Mix the cream with the reserved egg yolk and lightly brush the tops of the rolls. Bake for 30 minutes or until golden brown.