Preheat your oven to 400°F (200°C) and line a small baking sheet with parchment paper.
Toss the cubed sweet potatoes with one teaspoon of olive oil and a pinch of sea salt, then spread them in a single layer on the baking sheet.
Roast the sweet potatoes for 20-25 minutes, tossing halfway through, until they are tender and the edges are golden brown.
While the potatoes roast, heat a non-stick skillet over medium heat and cook the turkey sausage until browned and cooked through, then remove and slice into rounds.
In the same skillet, add the remaining teaspoon of olive oil and sauté the fresh spinach until just wilted.
Pour the egg whites into the skillet over the spinach, tilting the pan to ensure even coverage.
Allow the egg whites to cook undisturbed until the edges are set and the center is firm.
Place the sliced turkey sausage on one half of the omelette and carefully fold the other half over the filling.
Slide the omelette onto a plate and serve immediately alongside the roasted sweet potatoes.