Remove the skin and seeds from the pumpkin and cut it into small pieces.
Chop the onion.
Heat olive oil in a pot and sauté the onion.
Add the pumpkin and sauté together.
Pour in water and boil until the pumpkin is cooked through.
Turn off the heat and blend until smooth.
Pour the blended pumpkin back into the pot and add oat milk. Bring to a boil.
Season with salt and pepper.