How to find arbitrary object (toast) using image detection

I'm a beginner, I've done object detection using Haar Cascades on faces as well as ImageAI. So maybe not a complete beginner.

I'm working on a simple regression project for my resume, predicting low long a piece of toast has been in the toaster based on an image of the toast. I need a way to draw a rectangle on an image containing pictures of toast to extract them and use in my CNN model.

That has been proven to been a challenge with how arbitrary the object I'm trying to detect is. It's not one of the 80 classes in the YOLO classifier, ImageAI won't detect it, and there isn't a HaarCasade xml file for toast (shockingly).

How would I go about doing this?

Thanks in advance, fellow wizards. ‍♀️