In a small bowl, whisk together 1 cup sugar, 1 tablespoon zest, and rosemary. Cover, and let stand for 1 hour.
In the bowl of a stand mixer fitted with the paddle attachment, combine warm milk, yeast, and remaining 1 tablespoon sugar. Let stand until mixture is foamy, about 10 minutes. Add 1 cup flour; beat at low speed until combined. Add ¼ cup melted butter, beating to combine. Add ½ cup flour; beat until combined. Add eggs, beating until well combined. Gradually add salt, remaining 1½ cups flour, and remaining 1 tablespoon zest, beating until a soft dough forms.
Spray a large bowl with cooking spray. Place dough in bowl, turning to grease top. Loosely cover, and let rise in a warm (75°), draft-free place until doubled in size, about 1 hour.
Line a baking sheet with parchment paper.
On a lightly floured surface, roll dough into an 18x16-inch rectangle. Spread with remaining ¼ cup melted butter. Sprinkle generously with sugar mixture. Starting with one long side, roll dough into a log; pinch seam to seal. Using a serrated knife, cut log in half lengthwise. Carefully twist dough pieces around each other, and form into a circle. Place on prepared pan, cut side up, tucking in ends. Cover, and let rise in a warm (75°), draft-free place until doubled in size, about
45 minutes.
Preheat oven to 350°.
Bake until golden brown, 35 to 40 minutes. Garnish with rosemary and orange wedges, if desired.