Preheat your oven to 400°F (200°C).
Dice the Yukon gold potato into small 1/2-inch cubes and finely chop the yellow onion.
Heat the avocado oil in a large oven-safe skillet over medium-high heat.
Add the cubed potatoes to the skillet and sauté for 5-7 minutes until they begin to soften and develop a light crust.
Add the ground beef and chopped onion to the skillet, breaking the meat apart with a wooden spoon as it cooks.
Season the mixture evenly with sea salt, black pepper, garlic powder, and dried thyme, cooking until the beef is fully browned.
Pour in the beef bone broth to deglaze the pan, using your spoon to scrape up any flavorful browned bits from the bottom.
Transfer the skillet to the oven and bake for 10-12 minutes until the potatoes are fork-tender and the edges are crisp.
Remove the skillet from the oven and immediately fold in the baby spinach, allowing it to wilt naturally from the residual heat before serving.