Phase 1: Making the Sweet Yeast Dough

1. Activate the Yeast: In the bowl of a stand mixer (or a large mixing bowl if kneading by hand), combine the warm milk and 1 tablespoon of the granulated sugar. Sprinkle the active dry yeast over the top. Let it sit for 5-10 minutes until foamy. This “proofing” step ensures your yeast is active and ready to work its magic. If it doesn’t foam, your yeast may be old, or the milk too hot/cold; you’ll need to start over.
2. Combine Wet Ingredients: Once the yeast is foamy, add the remaining granulated sugar, melted butter, room temperature eggs, salt, and vanilla extract to the bowl. Whisk lightly to combine.
3. Add Flour and Mix: Attach the dough hook to your stand mixer. Gradually add 4 cups of the all-purpose flour to the wet ingredients. Mix on low speed until a shaggy dough begins to form.
4. Knead the Dough: Increase the mixer speed to medium-low and knead for 7-10 minutes. If the dough is excessively sticky after a few minutes, add the remaining flour, ¼ cup at a time, until the dough is soft, elastic, and pulls away from the sides of the bowl. It should be slightly tacky to the touch but not overly sticky. If kneading by hand, turn the shaggy dough out onto a lightly floured surface and knead for 10-15 minutes until smooth and elastic. Proper kneading develops gluten, which gives the rolls their structure and chewiness.
5. First Rise (Bulk Fermentation): Lightly grease a large bowl with oil or cooking spray. Transfer the kneaded dough to the bowl, turning it once to coat all sides with oil. Cover the bowl tightly with plastic wrap or a clean kitchen towel. Place it in a warm, draft-free spot to rise for 1 to 1.5 hours, or until doubled in size. The ideal temperature for rising is around 75-80°F (24-27°C).

Phase 2: Preparing the Fillings (While Dough Rises)

1. Prepare the Blueberry Filling: In a medium saucepan, combine the blueberries, granulated sugar, and lemon juice. Cook over medium heat, stirring occasionally, until the blueberries begin to burst and release their juices (about 5-7 minutes).
   Stir the cornstarch slurry (cornstarch mixed with cold water) into the blueberry mixture. Continue to cook, stirring constantly, for another 1-2 minutes until the filling thickens to a jam-like consistency. Remove from heat, stir in the pinch of salt, and let it cool completely. A cooled filling is crucial to prevent the dough from becoming too warm and difficult to handle.
2. Prepare the Cheesecake Filling: In a medium bowl, beat the softened cream cheese with an electric mixer (or by hand with a sturdy whisk) until smooth and creamy. Add the granulated sugar, egg yolk, lemon zest (if using), and vanilla extract. Beat until well combined and lump-free. Set aside. Room temperature cream cheese is key for a smooth, non-lumpy filling.

Phase 3: Assembling the Blueberry Cheesecake Rolls

1. Prepare Baking Dish: Generously grease a 9×13 inch baking dish (or two 8×8 or 9-inch round pans) with butter or cooking spray.
2. Roll Out the Dough: Once the dough has doubled, gently punch it down to release the air. Transfer the dough to a lightly floured work surface. Roll it out into a large rectangle, approximately 12×18 inches and about ¼ inch thick. Try to keep the edges as even as possible.
3. Spread the Fillings:

   • Carefully spread the cooled cheesecake filling evenly over the surface of the dough, leaving about a ½-inch border along one of the long edges.
   • Dot the cooled blueberry filling evenly over the cheesecake layer. You can gently swirl it slightly with a knife if desired, but be careful not to overmix or tear the dough.

4. Roll and Cut: Starting from one of the long edges (the one without the border), tightly roll the dough into a log. Pinch the seam (the border you left clean) firmly to seal.
   Using a sharp serrated knife or unflavored dental floss for the cleanest cuts, slice the log into 12 equal rolls (each about 1.5 inches thick). To use floss, slide a long piece under the log, bring the ends up, cross them over, and pull to slice through.
5. Arrange Rolls for Second Rise: Carefully place the cut rolls, swirl-side up, into the prepared baking dish. They should be cozy but not squished, allowing room to expand.
6. Second Rise (Proofing): Cover the baking dish loosely with plastic wrap or a clean kitchen towel. Let the rolls rise in a warm place for another 30-45 minutes, or until they look puffy and have increased in size by about 50%. They won’t quite double this time.

Phase 4: Baking the Rolls

1. Preheat Oven: About 20 minutes before the second rise is complete, preheat your oven to 375°F (190°C). Position an oven rack in the center.
2. Bake: Once the rolls are nicely puffed, uncover them. Bake in the preheated oven for 25-30 minutes, or until the tops are golden brown and the filling is bubbly. The internal temperature of the dough should reach 190-200°F (88-93°C) if checked with an instant-read thermometer. If they start browning too quickly, you can loosely tent the dish with aluminum foil for the last 5-10 minutes of baking.
3. Cool Slightly: Remove the rolls from the oven and let them cool in the baking dish on a wire rack for at least 15-20 minutes before glazing. This prevents the glaze from melting off completely.

Phase 5: Making the Cream Cheese Glaze & Finishing

1. Prepare the Glaze: While the rolls are cooling, prepare the glaze. In a medium bowl, beat the softened cream cheese and softened butter together with an electric mixer until smooth and fluffy.
2. Add Sugar and Liquid: Gradually add the sifted powdered sugar, beating on low speed until incorporated, then increase speed to medium and beat until smooth. Add the vanilla extract and salt.
3. Adjust Consistency: Add milk or cream, 1 tablespoon at a time, beating after each addition, until the glaze reaches your desired drizzling or spreading consistency. It should be thick but pourable.
4. Glaze and Serve: Once the rolls have cooled slightly (they should still be warm, but not hot), generously spread or drizzle the cream cheese glaze over the top. Serve warm and enjoy the deliciousness!