Fry the pancetta in a non-stick frying pan for 1-2 minutes until crispy, drain on kitchen paper. Add the walnuts to the pan juices and fry for 1-2 minutes until golden.
Divide the spinach between 2 plates, add the avocado and sprinkle with mozzarella and walnuts. Top with the pancetta and drizzle with balsamic glaze to serve.