In a small saucepan set over medium-high heat, bring the stock to a simmer. Reduce heat to low to keep warm.
Add 1 tablespoon olive oil to a 3-quart pot over medium heat. Add the chopped onion and garlic; cook until soft – about 5 minutes. Add the rice and half the lemon zest; stir so that each grain of rice is coated with oil and appears glossy. Cook the rice for 3-4 minutes, or until it is mostly translucent. Stir in the wine, scraping up any bits that have hardened in the bottom of the pan.
Add 1 cup of the warm stock. Stir constantly until all the stock has absorbed into the rice. Continue this process, adding the stock 1/4 cup at a time, until the rice is creamy and soft – the whole process will take about 20 minutes. Stir in the spinach, parmesan, and lemon juice, until the spinach is wilted.
Heat the oil and butter in a small skillet over medium-high heat. When the butter is melted, add the scallops. Cook 2 to minutes on each side, or until golden brown and cooked through.
Stir together 1/4 teaspoon of the remaining lemon zest with 1/4 teaspoon sea salt.
Serve the scallops on top of the risotto. Sprinkle with lemon salt and season to taste with black pepper.