Preheat oven to 450. Place the potatoes on a large piece of foil and drizzle with olive oil, salt and pepper. Bring edges of foil together to make a sealed packet, place on a baking pan and bake for 40 minutes.
Meanwhile, combine both cheeses, lemon zest and salt to taste. When potatoes are done, cool just until you can handle them, then cut a small X on each one and squeeze open.
Place a spoonful of the ricotta mixture on each potato, grind some pepper on top and drizzle a little more olive oil on top. Serve immediately.