Preheat the oven: Set your oven to 400°F (200°C) to warm up while you prepare the ingredients.
Season and prepare the sweet potatoes: Peel and cube the sweet potatoes into even pieces. Place them in the casserole dish. Season with 1 tsp salt, ½ tsp pepper, and 2 mashed garlic cloves. Drizzle 1 tsp olive oil over the sweet potatoes and toss them together to coat.
Add the vegetables and sausage: Add the chopped onion, diced green bell pepper, and crumbled light turkey sausage to the dish. Mix everything well so the ingredients are evenly distributed in the dish.
Roast the sweet potatoes and vegetables: Place the casserole dish in the preheated oven and roast for about 25-30 minutes, or until the sweet potatoes are tender and the vegetables and sausage are golden brown and slightly crisp around the edges.
Prepare the egg mixture: While the sweet potatoes and vegetables are roasting, beat the eggs in a large bowl. Add the milk and chopped Swiss chard, and whisk until well combined.
Combine and bake: Once the roasted vegetables and sweet potatoes are ready, remove the dish from the oven. Pour the egg mixture over the roasted ingredients, making sure everything is evenly coated with the eggs.
Bake the casserole: Return the casserole dish to the oven and bake for an additional 10-15 minutes, or until the eggs are fully set. You’ll know it’s done when the edges start to pull away from the sides of the dish, and the center is firm to the touch.
Serve and enjoy: Let the casserole rest for a few minutes after taking it out of the oven. Cut into slices and serve hot.