Step 1: In a large bowl or the bowl of a stand mixer, combine the warm milk, 2 tablespoons of the granulated sugar, and instant dry yeast. Stir gently and let sit for 5 minutes until slightly foamy.
Step 2: Add the melted butter, egg, and salt to the yeast mixture. Mix well to combine.
Step 3: Gradually add 4 cups of all-purpose flour, mixing with a wooden spoon or dough hook until a shaggy dough forms. Knead for 5-7 minutes until the dough is smooth and elastic. Add up to 1/2 cup more flour if the dough is too sticky.
Step 4: Lightly oil a large bowl. Place the dough in the bowl, turning once to coat. Cover and let rise in a warm place for 1 to 1.5 hours, or until doubled in size.
Step 5: While the dough rises, prepare the filling. In a small bowl, combine the softened unsalted butter, light brown sugar, and ground cinnamon. Mix until smooth. If using frozen blueberries, toss them with 1 tablespoon of flour.
Step 6: Once the dough has doubled, punch it down gently. Turn onto a lightly floured surface and roll into a 12x18 inch (30x45 cm) rectangle.
Step 7: Evenly spread the cinnamon sugar filling over the entire surface of the dough, leaving a 1/2 inch border along one long edge.
Step 8: Sprinkle the prepared blueberries evenly over the cinnamon filling.
Step 9: Starting from the long edge opposite the clean border, carefully roll the dough tightly into a log. Pinch the seam closed to secure it.
Step 10: Using a sharp knife or unscented dental floss, slice the log into 12 equal pieces, each about 1.5 inches thick.
Step 11: Lightly grease a 9x13 inch (23x33 cm) baking dish. Arrange the sliced rolls cut-side up in the dish. Cover and let rise again in a warm place for 30-45 minutes, or until visibly puffy.
Step 12: Preheat your oven to 375°F (190°C).
Step 13: Bake for 20-25 minutes, or until golden brown on top. If browning too quickly, loosely tent with foil.
Step 14: While rolls bake, prepare the glaze. Beat softened cream cheese and butter until smooth. Gradually add powdered sugar, vanilla extract, and a pinch of salt. Beat until light and fluffy. Add milk, if needed, for desired consistency.
Step 15: Let the rolls cool in the pan for 5-10 minutes. Generously spread the cream cheese glaze over the warm blueberry cinnamon rolls and serve immediately.