In a saucepan, combine frozen blueberries, granulated sugar, and corn starch over medium heat. Cook for 20-25 minutes, stirring occasionally, until thickened and bubbly. Remove from heat and allow to cool. Set aside 2 tablespoons for frosting.

Warm whole milk to about 110°F and combine it with sugar in a bowl. Let the yeast bloom for 5-10 minutes until foamy. In another bowl, mix all-purpose flour and salt. Add the yeast mixture, eggs, vanilla extract, lemon zest, and softened butter. Mix until a dough forms, then knead on a floured surface until smooth.

Shape the kneaded dough into a ball and place in a greased bowl, turning to coat. Cover with a towel and let rise until doubled in size—about 1 to 1.5 hours.

In a mixing bowl, beat softened butter with brown sugar and granulated sugar until creamed together. Add fresh lemon juice, lemon zest, and salt, mixing until smooth.

Once the dough has risen, punch it down gently and roll it out into a large rectangle, about 1/4 inch thick. Spread the lemon filling evenly across the dough, then spoon prepared blueberry jam on top. Roll the dough tightly into a log and cut into 12 equal pieces.

Pour heavy cream evenly between the rolls in the baking dish. Cover with a towel and allow to rise again until doubled in size, approximately 1 hour.

Preheat your oven to 350°F. Once the rolls have risen, bake for 22-25 minutes or until golden brown.

While the rolls cool, beat together softened cream cheese and butter until smooth. Gradually mix in sifted powdered sugar, blueberry jam, and lemon zest until fluffy.

Allow the rolls to cool for about 10 minutes before generously frosting them with the creamy frosting.