This was my mother's favorite baked good when she was a little girl in Poland. When her mother baked these buns, the house smelled delightful. Little hands loved to help roll little dough balls. The whole family eagerly anticipated their emergence from the wood burning stove, only to enjoy them warm with a glass of milk.
1. Proof the yeast by combining 2 packs dry yeast (4.5 teaspoons), 1/2 cup very warm water and 1 tablespoon sugar in a cup, mix well with fork, cover with clean, dry dish towel, and let rest 5 minutes.
2. Whisk 3.5 cups unbleached flour with 1/2 teaspoon salt and 1/2 cup sugar in a large bowl.
3. Melt 1/2 cup unsalted butter with 1 tablespoon pure vanilla extract and 1/2 teaspoon rum extract (optional) in a small pot and allow to cool to room temperature. Zest one orange into the mixture as it cools. Alternately, you may zest one lemon or you can add both.
4. Add 3 (room temperature) eggs to a well in the middle of the flour mixture and stir with fork working in the middle of the well. Add the bubbling, rising, yeast mixture to flour mixture and mix on low speed increasing to medium low with hook attachment, until combined. You may work the dough with your hands if hook attachment is not available.
5. Add butter mixture to flour mixture and increase speed to medium. Beat for 5 minutes. Dough should start to form a ball. If dough is sticky, add up to 1 cup of flour in small increments until dough pulls away from sides of bowl.
6. Transfer dough ball to a floured wooden board or clean surface and knead the dough with your hands for 1 minute. Form into a ball and transfer to a buttered large bowl. Cover loosely with buttered parchment paper or wax paper or plastic wrap then cover with a dry kitchen towel. Important: Allow to rise in warm, draft free place for 1 hour. Dough should double in size.
7. Butter a cookie sheet. Remove a 3 inch (7.5 centimeter) sized piece of dough, place in hands and roll it into a ball. Form a deep well in the middle. Fill with 1/4 teaspoon thick (warmed slightly) preserves of your preference such as rose, plum sour cherry or apricot, being careful not to get preserves on dough around the opening. Pinch sealed the opening over the preserves, ensuring dough touches dough and there are no preserves on the seam to be sealed. (If there are preserves on the seam, try pulling some clean dough over the sticky dough). Seal by pinching dough between thumb and index finger several times. Place sealed side down on cookie sheet. Dough balls should be about 3 inches in diameter and placed 2-3 inches apart.
8. Cover dough balls with buttered parchment paper and a kitchen towel or just a kitchen towel will do. Allow to rise in a draft free, warm place until doubled in size. Meanwhile, heat oven to 350 degrees F
(177 degrees C).
9. Glaze buns with 1 well beaten egg using a pastry brush. You may lightly dust buns with sugar crystals if desired.
10. Bake at 350 degrees F for 10-15 minutes, until they are golden in color. Let cool slightly and enjoy warm. May be reheated in microwave for 20 seconds.