Preheat oven to 375 degrees.
Bake the 4 potatoes for 1 hour.
Remove and allow to cool for about 10 minutes. Then reduce oven to 350 degrees.
Cut the potatoes in half lengthwise and scoop out the insides into a large bowl. (If they are still too warm use an oven mitt to handle).
Add in butter, milk, and cheese. Mash and stir until all is fully melted.
Gently add in the peas and bacon - stir to combine.
Add the potato mixture to a pregreased large casserole dish.
Bake for 15 minutes. Serve immediately.