Fill a large stock pot with water and bring to a boil. Add orecchiette and cook for 7-9 minutes, or until al dente.
While pasta water is coming to a boil, heat a skillet over medium heat and melt butter. Add leeks and cook until wilted. Transfer leeks to a plate and return pan to stove.
Make the sauce: Add garlic and olive oil and cook until fragrant, about 30 seconds. Add salt and flour, stirring until slightly browned. Add chicken stock and bring to a boil; add cream cheese, stirring to combine. Take pan off of heat and stir in shredded cheese.
Using a slotted spoon, transfer pasta directly into sauce. Add more pasta water to thin out the sauce, if necessary. Add leeks and spinach and cook until spinach is wilted. Serve with a garnish of Italian parsley.