Activate the yeast: Pour the warm milk into a large mixing bowl. Add 1 tablespoon of the granulated sugar and sprinkle the yeast over the milk. Stir gently and let the mixture rest for 5–10 minutes, or until bubbly and slightly foamy.
Add the remaining wet ingredients: Add the remaining granulated sugar, brown sugar, egg, melted butter, vanilla extract, and lemon zest. Mix until well combined. Make sure the butter is slightly cooled before adding it.
Prepare the dough: Gradually add the flour and salt, mixing until a soft, shaggy dough begins to form.
Knead the dough: Transfer the dough to a lightly floured work surface and knead for 8–10 minutes. Alternatively, use a stand mixer fitted with a dough hook. The finished dough should be smooth, soft, and elastic.
Complete the first rise: Place the dough in a lightly greased bowl and turn it once to coat the surface. Cover and let it rise in a warm, draft-free place for approximately 1 hour, or until doubled in size.
Roll out the dough: Line a 9 × 13-inch baking dish with parchment paper or lightly grease it. Transfer the risen dough to a lightly floured surface and gently press out the excess air. Roll it into an approximately 18 × 10-inch rectangle.
Add the filling: Spread the softened butter evenly over the dough, leaving a small border around the edges. Carefully spread the blueberry jam over the butter, then distribute the fresh blueberries evenly across the surface.
Cut the dough: Use a sharp knife or pizza cutter to cut the filled dough into 12 long strips of equal width.
Shape the rolls: Carefully roll each strip into a loose spiral, keeping as much of the blueberry filling inside as possible. Place each roll in the prepared baking dish with the spiral side facing upward.
Complete the second rise: Cover the baking dish loosely and let the shaped rolls rise for 20–25 minutes, or until slightly puffy.
Bake: Preheat the oven to 350°F (180°C). Bake the Blueberry Lemon Rolls for 25–30 minutes, or until lightly golden and baked through. Cover them loosely with aluminum foil near the end if the tops begin browning too quickly.
Prepare the frosting: While the rolls bake, beat the softened cream cheese and vanilla extract until smooth. Add the lemon zest, powdered sugar, and salt. Mix until creamy, then add the blueberry jam and continue mixing until evenly combined.
Cool briefly: Remove the baked rolls from the oven and let them cool in the baking dish for approximately 10 minutes.
Frost and serve: Spread the cream cheese frosting over the warm rolls. Serve while they are still slightly warm and soft.