Bake pumpkin and vegetarian sausages in oven at 180C for 20 minutes. Whilst in oven, cook pasta for 10minutes until al dente.
Drain water from pasta and add pumpkin and olive oil to the pot (with salt if you want). Shake with lid on until pumpkin has mashed up a bit - this works as a kind of sauce. Slice the sausages and add to pot with tomatoes. Cool to room temp before adding basil.