Preheat your oven to 400°F and line a small baking sheet with parchment paper for easy cleanup.
Dice the potato into uniform half-inch cubes and toss them in a bowl with the olive oil, sea salt, and black pepper.
Spread the potatoes in a single layer on the baking sheet and roast for 20-25 minutes, flipping halfway through, until they are golden and crispy.
In a medium bowl, whisk together the whole eggs and egg whites until the mixture is uniform and slightly frothy.
Heat a high-quality non-stick skillet over medium-low heat and pour in the egg mixture, letting it sit for 30 seconds before stirring.
Gently push the eggs across the pan with a silicone spatula to create large, soft curds.
When the eggs are about 80% cooked, fold in the baby spinach and continue to stir until the leaves are just wilted.
Transfer the scrambled eggs to a plate alongside the roasted potatoes and garnish with freshly chopped chives.