In a heated skillet, melt butter and sauté onions until translucent and soft, about 5 minutes. Stir in flour; slowly whisk in boiling water, stirring constantly until sauce thickens, about 5 minutes.
Transfer to a large stockpot and add potatoes, corn, cream style corn, powdered milk, cilantro, salt and pepper. Stir to combine. Simmer gently for about 20 minutes or until potatoes are tender. Remove from heat and serve.
Servings: 4