Carefully remove the long piece of meat in each rack without cutting through bones; discard bones. (Or just buy the fillets). Heat oil and butter in baking dish, add lamb, cook over high heat until lamb is browned all over. Bake, uncovered, in moderate oven for about 10 minutes or until lamb is cooked as desired; cover, stand 5 minutes before slicing. Serve lamb fillets with creamy pesto.

Blend or process basil, garlic, pine nuts, oil and cheese until well combined. Combine basil mixture and cream in pan, simmer, uncovered, for about 5 minutes or until slightly thickened.