Preheat oven to 450 degrees. Place potatoes in center of
a 3-foot-long piece of foil. Drizzle with 1 teaspoon olive oil and season with salt and pepper. Bring long sides of foil together and fold edges over, then tightly crimp ends to create a packet. Roast on a baking sheet until cooked through, 35 to 40 minutes.
In a small bowl, combine ricotta, Parmesan, and lemon zest; season with salt and pepper. When potatoes are cool enough to handle, cut a small X on top of each with a paring knife and gently squeeze open. Dollop about 1 teaspoon ricotta mixture into each. Drizzle 1 tablespoon olive oil over potatoes.