Melt the butter, brush onto the pieces of filo pastry and put them on top of each other. Plug round circles of the filo pastry and put in a muffin form or similar. The circles need to be a little bigger than bottom of the muffin forms to give the tartlets edges on top. Bake at 356 Fahrenheit (180 degrees Celsius) for 5-6 minutes until they have a hint of color. Let them cool.
Chop the salmon with a knife and stir with sour cream, mayonnaise, dill and shallot. Season with salt, pepper and lemon zest. Put a small amount of the salmon salad into the tartlets. Top with finely grated Castello Tickler Mature cheddar and some dill.
If you have any leftovers the salmon salad is also great on a piece of bread.