Begin by blanching fresh spinach in boiling water for about 1-2 minutes until wilted, then drain and squeeze out excess moisture. In a mixing bowl, combine the drained spinach with crumbled feta cheese, stirring until well combined.

Place your skinless salmon fillet on a clean cutting board. Using a sharp knife, carefully slice the fillet horizontally to create a thin, even layer. Season both sides generously with salt and pepper.

Spread the spinach and feta mixture evenly across the salmon layer, leaving a small border around the edges. Starting from one end, tightly roll the salmon into a spiral and secure it with toothpicks or kitchen twine.

Preheat your oven to 375°F (190°C). Grease a baking dish with olive oil and place the assembled pinwheels seam-side down inside. Brush the top with a little more olive oil and bake for 15-18 minutes.

After baking, carefully remove the toothpicks or twine from the pinwheels. Transfer them to a serving plate and garnish with fresh dill and a squeeze of lemon juice.