Heat olive oil in a large saucepan over medium-low heat.
Add the garlic and cook until fragrant, about 30 seconds. Add 3½ cups of water and bring to a boil.
Add the pastina and salt. Reduce the heat to medium-low and cook, stirring frequently, until most of the liquid is absorbed and the pastina is al dente, 10 to 12 minutes.
Meanwhile, heat a medium sauté pan fitted with a lid over medium-high heat. Add the Lemon Pepper Meatballs and the remaining ¼ cup of water, and immediately cover. Cook until the water is absorbed and the meatballs are heated through, about 4 to 5 minutes.
When the pastina is al dente, and most of the liquid is absorbed, remove and discard the garlic clove. Add the spinach and stir until wilted, about 1 minute. Turn off the heat, add the butter and Parmesan, and vigorously stir until melted and glossy. Taste and season with additional salt, if needed. The mixture should look slightly saucy; it will continue to thicken as it cools.
Divide the pastina and meatballs among 2 bowls, then garnish with additional Parmesan, freshly ground black pepper, to taste, and lemon zest.
