1.Cook pasta in a large saucepan of boiling salted water following packet instructions; drain well. Keep warm.
2.Meanwhile, heat oil in a large frying pan on medium. Saute onion 1-2 minutes. Add garlic and chilli; cook, stirring, 1-2 minutes, until fragrant.
3.Toss prawns and tomatoes through; cook 2-3 minutes, until prawns begin to change colour.
4.Increase heat to high. Add sherry; cook, stirring, 30 seconds. Pour in evaporated milk; simmer, uncovered, 2-3 minutes, until prawns and tomatoes are tender. Add dill.
5.Toss prawns and sauce through hot pasta. Serve topped with dill sprigs.