In a large saute pan heat up olive oil, add, chopped onions and cook until translucent; 3-4 minutes;
Add minced garlic and stir to cook for about 1 minute;
Add spinach and cook until wilted, for about another 2 minutes;
Add pasta and stir to coat it all with olive oil, onion and spinach mixture;
Add stock, cover the pan and cook according for about 8 minutes until the pasta is cooked through, actually more like 12-16 minutes, had to add some more water at the 8 minute point.
Turn off the heat, add cheese and black pepper, stir and taste. If needed add some salt. Serve immediately