In a large skillet, cook sausage, breaking it apart as it cooks, until no pink remains.
Meanwhile, finely chop onion, mushrooms, garlic and parsley in a food processor.
Add onion mixture and white wine to sausage. Cook over medium-high heat until vegetables are soft and liquid has evaporated. Reduce heat and stir in cream cheese until completely melted. Season to taste with salt and pepper. Refrigerate mixture for 1 hour.
Coat 2 baking sheets with cooking spray. Unroll pie crusts and place one on each baking sheet. Refrigerate until ready to assemble the pork.
Heat oil in a large skillet over high heat. Season pork with salt and pepper to taste. Sear meat on each side until brown, about 1-2 minutes.
In a small saucepan over medium-high heat, add butter and garlic. Cook for 2-3 minutes until butter is melted and garlic is fragrant. Reserve garlic butter.
To assemble: Place half of the sausage mixture in a line down the center of each pie crust. Place pork tenderloin on top. Roll the pie crust around the pork and pinch to seal, forming a log shape. Gently roll the assembled logs until the seams are facing down, tuck in the ends of the crust.
Brush pie crusts evenly with garlic butter. Cut several slits in each crust.
Bake for 30 minutes or until pork reaches desired doneness, 145 degrees F for medium. Let pork rest, covered with foil, for 15-20 before slicing minutes at your holiday table. Garnish generously with parsley.