Pre heat the oven to 375F ( 180C) Gas 4
In a large pan, melt half of the butter. Add the onion and cabbage and sauté for a few minutes, stirring constantly.
Allow the mixture to cook until the cabbage is wilted, and the onions soft. (If the cabbage and onion starts to get very dry add a splash or two of water to keep it moist).
Add the remaining butter to the pan and stir in the mushrooms, cook for about two more minutes then add the chopped dill and season with salt and pepper. Leave to cool.
Roll out the shortcrust pastry and line a 8 inch quiche/pie dish. Reserving sufficient for the lid of the pie.
Spread the softened cream cheese in the bottom of the unbaked pie shell.
Slice the hard boiled eggs and arrange the slices in a layer over the cream cheese. Cover with the cooked cabbage mixture.
Top the pie with the remaining pastry. Press the pastry together tightly at the edges, and flute the edges. Cut a few, short slashes through the top crust and brush with a little egg and milk.
Bake in the oven for 30 – 40 minutes, or until the crust is light brown.