1/3 cup (80 milliliters) sugar, plus 2 tablespoons (30 milliliters), divided
2 egg yolks
1/2 cup (120 milliliters) milk
2/3 cup (160 milliliters) melted butter, divided
Zest of 1/2 lemon
Zest of 1/2 orange
1/4 teaspoon (1 milliliter) salt
3 1/2 cups (840 milliliters) all-purpose flour
1 1/2 tablespoons (25 milliliters) apricot jam
Icing sugar, for serving
Combine yeast, warm water, and two tablespoons (30 milliliters) sugar in a small bowl. Leave for ten minutes.
Beat egg yolks and egg together in a small bowl.
Stir together beaten eggs, milk, 1/3 cup (80 milliliters) butter, lemon zest, orange zest, salt, and yeast mixture until well combined.
In a large bowl, combine flour and remainin sugar. Pour yeast mixture into flour mixture and stir with a wooden spoon until a dough forms. Transfer dough to work surface and knead with your hands until dough is pliable and smooth. Place in bowl and cover with plastic wrap. Let rise for two hours.
Punch down dough, then roll out onto a lightly floured surface unti two centimeters thick. Cut into an equal number of circles about nine centimeters in diameter. Fill the middle of each circle with 1 1/2 tablespoons (25 milliliters) of apricot jam, then wrap dough around the filling and pinch together at the top to secure. Once all the buns are filled, lightly brush the tops of each bun with the remaining melted butter.
Once all the buns are buttered, arrange seam-side down inside a high-sided baking dish, preferably one with a circular or oval shape. If you have a circular or oval-shaped dish, place one bun in the centre, then arrange the other buns in concentric rings leading out from it. If you have a square or rectangular dish, simply place the buns in rows. Cover and let sit for another 20-30 minutes.
Preheat oven to 325 F (160 F).
Place buns in oven on middle rack and bake until golden brown, about 25-30 minutes. Remove, let cool, then dust with icing sugar and serve.