Roast the pine nuts in a pan without fat while stirring constantly until golden brown, remove and let them cool down briefly. Prepare pasta in boiling salted water according to package instructions.
Meanwhile wash parsley, shake dry, pluck leaves and chop finely. Wash lemon hot, grate dry and grate peel thinly. Halve the lemon and squeeze (approx. 4 tbsp. juice).
Finely grate the pecorino cheese.
Finely crush 35 g pine nuts in a mortar and place in a bowl. Drain the pasta, collecting 40-50 ml of pasta water. Put the pasta back into the pot. Mix the crushed pine nuts, parsley, olive oil, pecorino cheese, lemon peel and juice with the pasta water.
Mix the sauce with the noodles, season with salt and pepper.
Drain the mozzarella well and pluck. Fill pasta into bowls. Add the remaining pine nuts and mozzarella and serve immediately.