Spinach and Ricotta Malfatti - Malfatti di spinaci e ricotta

• 120 g Parmesan cheese, cut in pieces (2 cm)
• ½ lemon, thin peelings of skin only
• 500 g fresh spinach leaves
• 40 g plain flour
• 200 g semolina, plus extra for dusting
• 250 g ricotta cheese
• 1 large egg
• ¼ tsp ground nutmeg
• 1 tsp fine sea salt, or to taste, plus extra for cooking
• 2 pinches ground black pepper, or to taste
• 2 pinches dried chilli flakes

To Serve

• 1 Tbsp olive oil, for frying
• 100 g salted butter, diced, for frying
• 10 - 12 fresh sage leaves, for frying
• fine sea salt, to taste
• dried chilli flakes, for serving (optional)