Preheat the oven to 180°C / 350°F / Gas mark 4.
Prepare a roasting tray lined with foil.
Place the peppers on the roasting tray, rub with olive oil and roast until the skins have browned.
Remove from the oven and place in a plastic food bag then seal tightly.
Leave for 30 minutes.
Remove the peppers from the bag and slip the skins off easily using your fingers.
Some of the skins can remain but the majority should be removed.
Using a large saucepan, heat 1 tablespoon of olive oil and cook the onion until soft.
Deseed the peppers now and roughly chop.
Add the peppers, thyme and stock in with the onions and heat through. In a small pan, dry toast the seeds, if using.
Then set aside. Using a food processor, blitz until smooth.
Season to taste, add the cream and heat through once more before serving scattered with the seeds.