For dough: In the bowl of a stand mixer fitted with the paddle attachment, stir together warm milk and yeast. Let stand until mixture is foamy, about 5 minutes.
Add 1½ cups flour, sugar, egg, butter, zest, juice, and salt, and beat at medium speed until well combined. Switch to the dough hook attachment, add remaining 2 cups flour, and beat at medium-low speed until dough is smooth and elastic, 5 to 6 minutes, stopping to scrape sides of bowl.
Turn out dough onto a lightly floured surface, and knead 5 times. Shape dough into a ball. Spray a large bowl with cooking spray. Place dough in bowl, turning to grease top. Cover and let stand in a warm, draft-free place (75°) until doubled in size, about 1½ hours.
Spray a well-seasoned 12-inch cast-iron skillet with cooking spray.
For filling: In a medium bowl, beat butter, sugar, cinnamon, and ginger at medium speed until creamy.
Turn out dough onto a lightly floured surface, and roll to a 17x10-inch rectangle. Spread filling onto dough, and sprinkle with grapefruit pulp. Starting at one long side, roll up dough into a log, pressing edges to seal. Using a sharp knife, cut rolls into 1-inch-thick slices, and place cut side up in prepared pan. Cover and let stand in a warm, draft-free place (75°) until doubled in size, about to 1 hour.
Preheat oven to 375°. Loosely cover pan with foil.
Bake until lightly browned, 25 to 30 minutes. Let cool on a wire rack for 15 minutes.
For glaze: In a large bowl, beat all ingredients with a mixer at medium-high speed until well combined. Drizzle onto sweet rolls, and serve warm.
Recipe by Paula Deen Magazine at https://pauladeenmagazine.com/grapefruit-sweet-rolls-recipe/