Activate Yeast: In the bowl of a stand mixer, combine warm milk, yeast, and 1 tablespoon of the granulated sugar. Let sit for 5-10 minutes until foamy.

Make Dough: Add the remaining sugar, softened butter, egg, and salt. Mix briefly. Gradually add the flour, kneading with a dough hook on medium-low speed for 5-8 minutes until a smooth, slightly tacky dough forms.

First Rise: Form the dough into a ball and place it in a lightly greased bowl. Cover and let rise in a warm place for 1 to 1.5 hours, or until doubled in size.

Prepare Filling: In a small bowl, mix the raspberry preserves, rose water, and cornstarch (if using).

Roll and Fill: Punch down the dough and turn it out onto a floured surface. Roll into a 12x18 inch rectangle. Spread the raspberry-rose filling evenly over the dough, leaving a 1/2-inch border.

Shape and Cut: Roll the dough tightly into a log starting from the long end. Pinch the seam to seal. Using unflavored dental floss or a serrated knife, cut the log into 12 equal rolls.

Second Rise: Place the rolls cut-side up in a greased 9x13 inch baking dish. Cover loosely and let rise for 30-45 minutes until puffy.

Bake: Preheat oven to 350°F (175°C). Bake the buns for 22-28 minutes until golden brown. Let cool in the pan for 10 minutes.

Make Frosting: Beat the softened cream cheese and butter together until smooth. Gradually add powdered sugar and vanilla, beating until fluffy.

Garnish: Spread the cream cheese frosting over the warm buns. Sprinkle immediately with chopped pistachios and dried edible rose petals. Serve warm.