Preheat the oven to 375°F. Peel the sweet potato and cut it into cubes of about 0.4 inch. Place the cubes in a bowl, add olive oil and a pinch of salt, and stir well.

Spread the cubes in a single layer on a parchment-lined baking sheet. Roast for 20–25 minutes in the oven until the cubes are tender and lightly caramelized at the edges. Remove the baking sheet from the oven and set aside.

While the potato roasts, crack the eggs into a bowl and whisk them with a pinch of salt and pepper until the mixture is lightly frothy. Wash the spinach, shake or pat dry, and roughly chop if the leaves are large.

Heat a drizzle of olive oil in an ovenproof pan over medium heat. Add the spinach and cook for 1–2 minutes until wilted. Add the roasted sweet potato cubes and warm briefly so everything is evenly distributed.

Pour the egg mixture with the grated Emmental cheese over the vegetables in the pan and use a spatula to spread the mixture evenly. Place the pan in the oven for 10–15 minutes, until the eggs are set and the top feels firm.

Remove the pan from the oven and let the frittata rest for 3–5 minutes so it firms up. Cut into wedges and serve immediately. Enjoy!