In a large skillet over medium heat, heat butter and oil. Once butter is melted add tomato paste, cooking and breaking up with a wooden spoon. Cook for about 4 to 5 minutes until dark red and fragrant. Add parsley. Turn off heat and set aside.
Bring a pot with water to simmer. Season with salt as desired.
In a medium bowl combine ricotta, Pecorino Romano, flour, nutmeg, salt until a sticky wet mixture forms. Scoop a heaping tablespoon of gnudi mixture into your hand. Gently form into a ball. It will be sticky. Place in the pot of simmering water and cook for about 5 minutes or until the gnudi float to the surface of the water. Scoop about 1/4 to 1/3 c. hot water from the pot and add to the tomato butter. Remove gnudi with a slotted spoon and place gently in skillet with tomato butter.
Serve with Pecorino.