In a medium bowl, add the cottage 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 cottage 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.