Peel and chop potatoes, place in pot, cover with cold salted water, bring to boil, simmer for 15-20 minutes, drain.

Add butter and milk to potatoes, mash until smooth, stir in cheese, salt, and pepper.

Preheat oven to 375°F (190°C).

Roll out pie crust, fit into pie dish, spoon filling into crust, top with second crust if desired, brush with egg wash.

Bake for 25-30 minutes until crust is golden and filling is bubbling.

Allow pie to cool for 10 minutes before serving.