An exemplary method of forming an endwall with a contour includes casting an endwall with at least one cooling channel having an opening from the endwall, and covering the opening with a cupped contour formed on the endwall. An exemplary gas turbine engine blade assembly includes an endwall with a plurality of cooling channels, an airfoil extending radially from the endwall to a tip, and a cupped contour formed on the endwall to provide a cooling chamber between the cupped contour and a radially facing surface of the endwall.