Preheat the oven to 400°F. Fill a large 9×13-inch baking dish with the baby spinach, laying the leaves in an even layer.

In a small bowl, mix the pomegranate molasses, olive oil, lime zest and juice, cinnamon, red pepper flakes (optional), and salt until uniform.

Place the salmon fillets on the bed of spinach, evenly spaced. Spread the glaze all over the salmon. Pour any leftover glaze over the spinach.

Bake in the oven for 15 minutes, or until the salmon is flaky and cooked through. The glaze will have darkened and caramelized, and the spinach will have cooked down.