Prepare all the vegetables and place in a large roasting tin. You can leave the skin on the squash as the skin is edible, and is easy to scoop the roasted sqaush off the skin afterwards if you don't want to include it
Place in a preheated oven at 190 degrees C for 40 minutes, turning regularly to avoid charring. Cook until squash is tender and easily pierced with a knife.
Take out of the oven, and set aside to cool
Remove any tough skin from the onions, then place in a food processor with peppers and courgettes. Squeeze the soft garlic cloves out of their paper linings into the food processor. Scoop the squash from its skin and add to food processor.
Add the chickpeas, black pepper, and blend, adding up to 150mls of water if you need to thin the sauce (If you want to use it as a roasted vegetable hummus, skip the water, but add the olive oil here)
Warm the sauce for a couple of minutes in the portion size you need, drizzle over the olive oil, and mix into the pasta.