For the par-cooked red potatoes: Bring a large pot of salted water to a boil. Add the potatoes, cover and cook until the skin pierces easily but the center is still firm, 7 to 10 minutes. Remove from the water and allow to cool slightly before slicing.
For the roasted red bell pepper: Place 1 red bell pepper skin-side down on a burner of a gas stove over medium-high heat. Turn the pepper as it chars until it's black all over. Place in a bowl, cover with plastic wrap and steam for 5 minutes. When the pepper is cool enough to handle, remove the charred skin and the seeds. Cut half of the roasted pepper into slices and reserve the remaining half for another recipe.
In a medium bowl, add the ricotta cheese, 1 tablespoon of the oil and some salt and pepper.
Pour the remaining 2 tablespoons oil in a 10-inch ovenproof skillet set over medium heat. Add the eggs to the skillet and sprinkle with salt and pepper. Top with the peppers, potatoes and spinach. Dollop the ricotta cheese evenly over the top. Cover the pan, then transfer to the oven and cook for 20 minutes.
Cut the frittata into four wedges, and garnish with chives to serve.
You can also use cottage cheese instead of ricotta cheese.