A heat exchanger assembly for a gas turbine engine including a frame, including a non-planar outer wall, a non-planar inner wall spaced radially inward from the non-planar outer wall to form a frame cavity therebetween, an inlet side extending between the non-planar outer wall and the non-planar inner wall, an inlet passage extending through the inlet side, an outlet side extending between the non-planar outer wall and the non-planar inner wall opposite the inlet side; an outlet passage extending through the outlet side, and a continuous non-planar core disposed within the frame cavity and in flow communication with the inlet passage and the outlet passage.