19 week old mystery breed pullet... Updated with egg pic

[chickensducks&agoose]

I have 2 partridge chanteclers, and they look nothing like OPs bird. They are much more of a molassesy red color, and I'm voting EE too.

 

[elizabethlongwood]

Updated my post with a newer picture and a picture of her egg. If she's a dark cornish, she sure is starting out a better layer than most. We've had 5 eggs in the 5 days since she started laying!!