In a mixer bowl with a dough hook attachment, combine the egg, milk, sour cream, sugar, yeast, flour, and salt. Activate the mixer on low speed and gradually add the butter. Continue mixing for an additional 2 minutes. Then, increase the mixer speed to high-medium and knead for about 10 minutes until the dough becomes smooth and uniform. Remember, the kneading time is crucial for that perfect texture and gluten development. Let the dough rise until it doubles in size (approximately one hour).
For the filling, mix the ground pistachios, powdered sugar, and room temperature butter in a bowl until you achieve a smooth paste.
Once the dough has risen, divide it into two equal parts. Roll out each part into a thin and even rectangle. Spread the delightful pistachio filling on top, ensuring it covers the dough completely. If the filling has cooled and hardened, you can gently microwave it in short bursts to soften it.
Using a pizza cutter or a sharp knife, slice the dough into strips of even thickness. Roll them up into delectable rolls and flatten them slightly. Place the pistachio rolls in a suitable baking pan, leaving gaps between them to allow for rising. Let them rise for about 45 minutes.
Preheat your oven to 350°F (175°C) in turbo mode. Bake the rolls for approximately 35 minutes or until they achieve a lovely golden brown color on top and bottom.
While the rolls cool off, prepare the frosting by mixing cream cheese, heavy whipping cream, and powdered sugar together in a bowl. Refrigerate the frosting until ready to use.
Once the rolls have cooled, generously spread the luscious cream cheese frosting on top. Sprinkle some crushed pistachios for that perfect finishing touch. Enjoy!