Add the butter, cream and salt to a large sauté pan, turn the heat on to medium and melt the butter into the cream. Bring to a simmer and cook until slightly thickened, about 1 minute. Take off the heat.
Bring a large pot of salted water to a boil and add the tortellini. Cook until the tortellini are slightly underdone, 3-5 minutes. Drain well.
Place pan with butter and cream back over medium heat. Add the tortellini and Parmagiano-Reggiano cheese and stir gently until cheese is melted and tortellini are well coated with the sauce.
Coat the bottom of a round or oval baking dish with 1 cup of the bolognese sauce. Add the tortellini with the cream sauce to the dish, then make a circle on top of the tortellini in the center with the remaining half cup of bolognese sauce, leaving about 1 inch around the edges uncovered.
Place the baking dish in the oven and cook for 15 minutes, until the cream sauce is starting to bubble around the edges.