Stovetop Frittata

8 large eggs ⅓ cup heavy cream (80ml) salt pepper 3 tbsp olive oil 1 onion, finely chopped 4 garlic cloves, minced 1 sausage, diced 100 g bell pepper, chopped 100 g cherry tomatoes, halved 100 g zucchini, roughly chopped 50 g spinach ½ tsp black pepper 100 g kefalotyri cheese, grated 50 g feta cheese 2 tbsp parsley, chopped