- Finely chop the onion.
- Take cubed squash and place in a roasting tin. Drizzle over the rosemary sprigs and season with salt and black pepper.
- Season with salt and pepper. Roast in a preheated oven at a temperature of 400°F for 45 minutes.
- At the same time, in a saucepan, place the lentils. Add enough water to cover it, heat and boil it rapidly for 10 minutes. Strain, then put lentils in a clean saucepan along with onion and vegetable soup and let simmer for about 5 minutes. Season that suits you.
- Remove the squash from the oven and put out the flesh, With the help of fork mash it and then add to the soup. Simmer for about 25 minutes and then put into serving bowls.
- If desired, garnish with rosemary sprig before serving.