In a large, oven-proof skillet, add onions and butter. Cook over medium heat 10 minutes, stirring often. Reduce to low and cook 15-20 minutes, stirring occasionally, until onions are caramelized and deep golden in color.
Add the broth, poultry seasoning salt, and pepper. Cover and bring to a simmer. Stir in the tortellini and return the lid. Simmer 2-3 minutes or until the tortellini is al dente, stirring occasionally.
Mix the shredded Swiss and Gruyere. Add 1 cup of shredded cheese and the cream cheese. Stir until fully melted. Turn off the heat and stir in the dip.
Top with the remaining shredded cheese. Bake 20-25 minutes, or until the cheese is melted and starts to brown.