This is an isoline carving, which is inherently done the way you've described.
As far as I know Easel will always be making g-code to cut along input vectors (not interpreting 3D geometry and planning vectors along it), but I'm not sure if it will ever allow anything besides 2D vectors in a 3D space (flat vectors at different heights). Unless it can interpret true 3D vectors, it won't ever be doing true 3D carving. Svgs, the basis for Easel designs (as far as I know), kind of allow for 3D vectors through gradients, but it's a sort of meta-attribute, not a true 3D vector. I think it can be tricked to do some pretty close approximations, but they're going to be very inefficient.