Tuna and Rice Slice

Ingredients
1 cup rice
2 eggs
1 onion
5 tblsp butter
500g can tuna
3 tblsp flour
500 ml milk
1 tsp dry mustard
1 tsp paprika
salt and pepper
60g cheese
2 tblsp chopped parsley
2 tblsp lemon juice

Cook the rice in boiling salted water until it is tender.Drain well and rinse under hot