Cook pasta according to directions, drain, reserve 1/2 - 1 cup of cooking liquid.
Heat oil in a large pan, add onions and cook until soft. Add garlic and cook for further minute or two.
Add chicken, pumpkin puree, sage and pasta cooking water, stir gently until heated through and slightly thickened. Add pasta and spinach, stir for a minute or two until spinach is wilted.
Add cheese, stir to combine, then add lemon zest.
Season to taste
Serve in pasta bowls, sprinkled with toasted breadcrumbs and extra lemon zest or toasted nuts.