Fill some plastic six paks with soil and poke a deep hole in each cell.

Carefully spoon out a small chunk of seedlings. Tease them apart, holding them only by the leaf part. Using a pencil or end of a small paintbrush, carefully guide the root into the cell, one plant per cell. Carefully (with the pencil) close in the soil around the root. Place in a pan of water for a few minutes. Then put the paks under lights.

Be brave enough to throw out a lot of seedlings (or cut them off at soil level and eat them.)

I would thin them! Start over if you want, but don't get rid of these! Grow them (thinned or not) and see what happens!