1. Take a bowl and flake the fish after draining it thoroughly.
2. Mix in the peas and evaporated milk.
3. Season with lemon juice along with salt & pepper.
4. Take a pan and stir the mixture in it over low heat until it becomes creamy and smooth.
5. Spread a split half of roll with butter.
6. Place a slice of cheese on top of each.
7. Put the hot fish mixture on it and place the other half of the roll on top.