Tender, buttery croissant dough is rolled with sugar that caramelizes during baking, creating a rich, complex background for your favorite fruit or jam.
Generously butter the wells of a 12-cup muffin pan. Spoon a teaspoon of granulated sugar into each of the wells, then tap the pan in all directions to coat the insides. Turn the pan over and lightly tap out any excess.
To make the filling: Combine the sugars, cinnamon, and orange zest, stirring well with a fork to distribute the zest.
To assemble: Roll the dough to an 18" x 8" rectangle.
Brush the rectangle with melted butter. Sprinkle the dough generously with the sugar mixture and go over it lightly with a rolling pin to press it into the butter. Roll the dough up from the long edge into a tight cylinder. Cut into 1 1/2" slices. Place the slices, cut side up, in the wells of the prepared pan.
Let the buns rise for 1 to 1 1/2 hours in a room no warmer than 75°F (any warmer and the butter may begin to leak out). The buns should increase to one and a half to two times their original size. Toward the end of the rising time, preheat the oven to 375°F.
If desired, just before baking, butter the back of a spoon and press down on the center of the buns. Place 2 teaspoons of the preserves in the indentation.
Place the pan on a parchment-lined baking sheet and bake for 40 to 45 minutes, until the buns are deep golden brown.
Place a cooling rack over a piece of parchment. Remove the buns from the oven and immediately (and carefully) transfer them out of the pan onto the rack. If desired, roll the warm buns in granulated sugar and sprinkle the tops once more. Let cool slightly and eat warm or at room temperature.
Store, lightly covered, at room temperature for up to two days; freeze for longer storage.
