I found the recipe here if you want to give it a try.
In Darby's recipe she says it takes about 30-45 mins for the mixture to reduce in a heavy saucepan. I used my Le Crueset pot and it took 2 hours to reduce to the consistency needed. Also I couldn't get my oven temp to go lower than 170 degrees, so I cooked it at that for 10 hours and it worked fine. The outer edges were a little tougher than the inside part. I first gave Chloe a piece from the outside and she spit it out after sucking on it. I was bummed and thought I had failed, but then later Chad gave her a softer piece to try and and she ate it right up.
Let me know if you try and have better results.