Cut the edges off bread slices and then cut each slice in 2 pieces.
Heat a non-stick pan, toast the bread pieces on it from one side. When the pieces are toasted take them off the pan.
Heat another non-stick pan, and add 2 tbsp butter.
Add chopped onion and saute for half a minute.
Add chopped bell peppers and green chilli, and saute for no more than a minute. (The vegetables should get tender but not start to release moisture.)
Transfer the sauteed vegetables to a bowl, and add salt and mustard powder.
Add fresh cream and mix well.
Butter the toasted side of a bread piece and spread the sauteed vegetables on top.
Add grated cheese on top the vegetables.
Cover and cook on low flame till cheese melts.
Serve hot. (You can sprinkle some chilli flakes on top.)