Preheat oven to 140°C.
Place onion, garlic, EVOO and butter into the Thermomix bowl. Chop 5 sec/speed 5. Saute 5 min/Varoma/speed 1.
Add wine and cook 5 min/Varoma/speed 1. Add tomatoes, parsley, salt and pepper and combine 5 sec/speed 3.
Meanwhile, heat a large oven proof pot over a high heat. Splash a little EVOO in the pot and brown the lamb.
Add tomato mixture and stir to combine. Place lid on the pot and into the oven. Cook 4 hours.
Add peas just when you are ready to serve.
Cook spaghetti as per packet instructions.
Serve over spaghetti, garnished with basil leaves.