This is not a bad route but one of the fewer traveled on the East Face of the First Flatiron - in fact, the very last documented route that I got around to doing. The route is mostly solid and pretty good overall. The most noteworthy section on it is the middle, where the route climbs solid horizontals and incuts over brick-like cobbles for a fairly long section, reminiscent of the lower section of the route 'Butterfly,' also on the East Face of the 1st Flatiron.
From the 6th switchback, step off of the trail and onto a pine-needle ledge at the margin of the East face as for Atalanta. A chossy gully diagonals up and to the North slightly below you. Just above this, aim up and right to a nice feature above a small group of conifers and into a hanging, left-facing dihedral. This is one dihedral left of Atalanta.
A 70m rope will just barely take you up the first pitch to a good ledge and belay, passing the "brick wall" of solid square cobbles along the way.
A second pitch will take you up and just left to rejoin Atalanta and onto the final false summit of the East Ridge, from where you can belay and then un-rope and scramble over, (or lead) a final pitch to the true summit and rap down.
This route starts quite a way up the trail between the 1st and 2nd, as for Atalanta. A final switch-back that nearly touches the rock's base is easy to locate just a few hundred yards after hiking past and above the chossy red roofs over Kamakaze and Zig-Zag.
The route protects just slightly less than similarly graded Flatiron routes with the exception of the compact stone around the cobbles, where little protection is available. This is not a difficult section, however, as it is square and incut, is unlikely to produce any major anxieties.