Preheat the oven to 400°F. In a large bowl, toss the sweet potatoes and onions with olive oil and season with salt and pepper. Spread onto a single layer on a sheet pan. Bake for 45 minutes, stirring half way through.
Heat a skillet over medium high heat and add the remaining 2 teaspoons of olive oil. When the oil shimmers, add the ground lamb and break apart using a wooden or rubber spatula (you can also use a potato masher to get the meat well scrambled.) Season with salt and pepper while it cooks. When the lamb is almost all the way cooked, stir in the herbs and remove from the heat until the potatoes are done roasting.
When the sweet potatoes and onions are done roasting, mix in the ground lamb and apples to sweet potatoes and onions of the sheet tray. Return to the oven for 10 to 15 minutes until the apples are fork tender. Remove the rosemary and thyme sprigs before serving.
Optional: serve with eggs for a main dish or alone for a healthy hearty side dish. To cook the eggs with the hash, make 8 little wells in the hash with a spoon. Crack an egg into each well, season with salt and pepper and then finish cooking 10 to 15 minutes.
Whether you peel or don't peel the sweet potatoes is up to you! I prefer mine with the skin so they just get a real good scrub before dicing.