Cook pasta in a large pot of lightly salted water until just tender, drain and keep warm.
Melt butter in pan, add garlic and shallots and cook for 5 minutes over a low heat. Add flour, cook for 1 minute and stir in evaporated milk and spinach. Cook until sauce boils and thickens. Add cheese, salt and pepper to taste and simmer for 1 minute.
Serve hot sauce over pasta and top with pine nuts.