Preheat the oven to 425F with the pan in the oven, and toast the pine nuts.
Whisk the egg whites in a clean bowl to form stiff peaks. In a separate bowl, mix the egg yolks with the spinach, tomato, goat cheese, salt, and pepper to combine. Gently fold the egg whites into the spinach mixture.
Spray the hot pan with oil, then spoon the mixture in and sprinkle with the pine nuts.
Bake in the oven for 10 minutes, or until well risen, golden, and firm. Serve.
Rather than fresh spinach, one can use 3.5oz per serving cooked spinach, chopped or pureed.