My favorite mashed:
Use large russets, cut into 2 inch chunks. Easily scalable.
For each russet use:
2 TBSP butter
1 tsp minced garlic
1/2 tsp white truffle oil.
Boil potatoes until tender, mash.
Melt the cream and butter together, then mix into potatoes, mix in the garlic and the truffle oil.
Potatoes like no other.