Orzo with peas, spinach & feta

30 g unsalted butter 4 large spring onions, thinly sliced 2 large garlic cloves, minced 500 ml vegetable broth 200 g orzo pasta Zest from half a lemon 200 g coarsely chopped spinach leaves 100 g feta cheese 100 g cooked peas 2 tbsp fresh parsley, finely chopped Salt Pepper

For serving:

20 g feta cheese 1 tbsp freshly chopped onion