A green assembly suitable for forming a monolithic heat exchanger assembly, the green assembly comprising: a first plurality of laminated ceramic tape layers having a plurality of first tape remainder portions partially defining at least two, perpendicular first holes (62A-62D), the plurality of first tape remainder portions comprising at least one unitary horizontally extending portion and vertically extending portion, wherein the first plurality of layers are arranged in a build direction to define a first green manifold section, the build direction defined parallel to a counter-flow plane; and a second plurality of laminated ceramic tape layers arranged adjacent to the first plurality of laminated ceramic tape layers in the build direction, the second plurality of layers having a plurality of second tape remainder portions (74A, 74B) partially defining at least one second hole (72A, 72B), the plurality of second tape remainder portions comprising at least one unitary horizontally extending portion and vertically extending portion, wherein the second plurality of layers are arranged in the build direction to define a green core section in communication with the first green manifold section; wherein the green core section comprises: a plurality of spaced apart counter-flow plates stacked along a stacking direction normal to the counter-flow plane and the build direction, the plurality of counter-flow plates defining a plurality of flow passages parallel to the counter-flow plane; and a plurality of counter-flow fins disposed in at least one of the plurality of flow passages, between adjacent ones of the plurality of counter-flow plates. a first plurality of laminated ceramic tape layers having a plurality of first tape remainder portions partially defining at least two, perpendicular first holes (62A-62D), the plurality of first tape remainder portions comprising at least one unitary horizontally extending portion and vertically extending portion, wherein the first plurality of layers are arranged in a build direction to define a first green manifold section, the build direction defined parallel to a counter-flow plane; and a second plurality of laminated ceramic tape layers arranged adjacent to the first plurality of laminated ceramic tape layers in the build direction, the second plurality of layers having a plurality of second tape remainder portions (74A, 74B) partially defining at least one second hole (72A, 72B), the plurality of second tape remainder portions comprising at least one unitary horizontally extending portion and vertically extending portion, wherein the second plurality of layers are arranged in the build direction to define a green core section in communication with the first green manifold section; wherein the green core section comprises: a plurality of spaced apart counter-flow plates stacked along a stacking direction normal to the counter-flow plane and the build direction, the plurality of counter-flow plates defining a plurality of flow passages parallel to the counter-flow plane; and a plurality of counter-flow fins disposed in at least one of the plurality of flow passages, between adjacent ones of the plurality of counter-flow plates. a plurality of spaced apart counter-flow plates stacked along a stacking direction normal to the counter-flow plane and the build direction, the plurality of counter-flow plates defining a plurality of flow passages parallel to the counter-flow plane; and a plurality of counter-flow fins disposed in at least one of the plurality of flow passages, between adjacent ones of the plurality of counter-flow plates.