Begin by peeling and chopping your potatoes into even chunks. Place them in a pot, covering them with water and adding a pinch of salt. Bring the water to a boil over medium-high heat, then reduce to a simmer for 15-20 minutes, or until the potatoes are fork-tender. Drain the cooked potatoes and set them aside for the filling.

Return the drained potatoes to the pot and add in butter and milk. Use a potato masher to mash everything together until it reaches a creamy consistency. Stir in your shredded cheese, adjusting with salt and pepper to taste. Allow the mixture to cool slightly while you prepare the crust.

Preheat your oven to 375°F (190°C). Take your prepared pie crust and roll it out gently on a floured surface if homemade, then place it into a pie dish, pressing it against the sides. Spoon the creamy potato filling into the crust, smoothing the top with a spatula.

If you opt for a second crust, layer it over the filling and seal the edges by crimping with your fingers or a fork. Brush the top with beaten egg for that golden finish. Bake the pie in the preheated oven for 25-30 minutes, or until the crust is beautifully golden brown and the filling is bubbling slightly.

Once baked, remove the Irish Potato Pie from the oven and let it cool for 10 minutes. Serve warm, either plain or garnished with fresh herbs.