Boil potatoes until tender, about 15 minutes.
Drain potatoes completely and mash until smooth.
Cook bacon in skillet until crispy.
Remove bacon and cook sausage thoroughly.
Mix butter and milk into mashed potatoes.
Add eggs and cheese to potato mixture.
Season with salt and pepper generously.
Spread half potato mixture in greased pan.
Layer bacon and sausage over potatoes evenly.
Top with remaining potato mixture completely.
Brush top with olive oil lightly.
Bake at 375°F for 45 minutes.
Let rest 10 minutes before slicing.