Then add just enough vegetable stock to cover the ingredients in pot followed by the crumbled up chicken stock cube , salt and pepper , then stir to combine all . Now bring to the boil then turn down to a simmer (medium / low) and simmer , uncovered , for about 35-45 minutes , or until the pumpkin and garlic are very tender , then stir through the remaining herbs and let simmer a further couple minutes , then remove from heat and let cool slightly before blending