Preheat your oven to 400°F.
In a skillet over medium heat, warm the olive oil and add the chopped onion and diced carrots. Sauté until they begin to soften, about 3-4 minutes.
Add the grass-fed ground beef to the skillet. Cook, breaking up the meat with a spoon, until it is browned and nearly cooked through. Drain any excess fat if necessary.
Stir in the green peas and low-sodium beef broth. Allow the mixture to simmer for about 5 minutes so the flavors meld together. Season with salt and pepper to taste.
While the beef mixture simmers, steam the cauliflower until tender, about 8-10 minutes.
Once the cauliflower is soft, mash it with a fork or potato masher until smooth. You may add a pinch of salt and pepper to season the mash.
Transfer the beef and vegetable mixture into an oven-safe dish. Spread the mashed cauliflower evenly over the top, creating a creamy layer.
Place the dish in the preheated oven and bake for 10-12 minutes, allowing the flavors to integrate and the top to become slightly golden.
Remove from the oven, let it cool slightly, and serve warm.