Bring potatoes to a boil in a large Dutch oven filled with water. Reduce heat to medium; simmer 20 minutes or until tender. Drain; return potatoes to pan. Add chicken stock, salt, and pepper; mash to desired consistently.
Melt butter in a skillet over medium-high. Add leeks; saute 5 minutes. Stir leek mixture into potato mixture (do not wipe out skillet).
Return skillet to medium-high. Add oil and shallots; cook 3 minutes or until shallots are browned and browned and crisp. Spoon mashed potatoes into a serving dish. Top with crispy shallots. Enjoy!