In a small bowl, dissolve yeast in warm milk.
In a large bowl, combine sugar, butter, egg yolk, vanilla, salt, nutmeg, yeast mixture and 1 cup flour; beat on medium speed 2 minutes.
Stir in enough remaining flour to form a soft dough (dough will be sticky).
Turn onto a floured surface; knead until smooth and elastic, 6-8 minutes.
Place in a greased bowl, turning once to grease the top.
Cover and let rise in a warm place until doubled, about 1 hour.
In a 10-in. cast-iron or other ovenproof skillet, cook bacon over medium-low heat until crisp.
Remove with a slotted spoon; drain on paper towels.
Discard drippings, reserving 3 tablespoons.
In the same skillet, combine brown sugar, syrup, cinnamon, nutmeg and 2 tablespoons reserved bacon drippings; cook and stir until blended.
Cool to room temperature.
Wipe out skillet; grease with remaining bacon drippings.
Punch dough down.
Roll into an 18x12-in. rectangle.
Sprinkle brown sugar mixture and bacon to within ½ in. of edges.
Roll up jelly-roll style, starting with a short side; pinch seams to seal.
Cut into 12 rolls.
Place rolls, cut side down, in prepared skillet.
Cover and let rise in a warm place until doubled, about 45 minutes.
Preheat oven to 400°.
Bake on a lower oven rack until golden brown, 18-20 minutes.
In a small bowl, beat frosting ingredients until smooth.
Spread over warm rolls.
Serve warm.
