Keto Shepherd's Pie

Preheat oven to 400°. Bring a large pot of salted water to a boil. Add cauliflower florets and cook until tender, 10 minutes. Drain well, pressing with paper towels or a clean dish towel to remove as much excess water as possible. Return cauliflower to pot and add cream cheese. Use a potato masher to mash cauliflower until smooth. Add heavy cream, 1 cup cheddar, and half of the green onions and stir to combine. Season well with salt and pepper.  In an oven-safe skillet over medium heat, heat oil. Add onion and carrots and cook until soft, 5 minutes. Add garlic and cook until fragrant, 1 minute more. Add tomato paste and stir to coat veggies. Add ground beef to skillet and using a wooden spoon to break up meat, cook until no longer pink, 6 minutes. Season with salt and pepper. Add broth and simmer 2 minutes.  Top skillet with cauliflower mash, then top with remaining ½ cup of cheddar. Bake until top is golden and cheese is melty, 20 minutes.  Top with more green onions to serve.