Happy birthday, Pix :)
I got the recipe from one of the websites.... just type in "peanut butter delight" doggie birthday cake and you should have quite a few results pop up. It's actually very very easy to make. The ingredients are just 1 cup of wheat flour, 1 tsp baking soda, 1/4 cup peanut butter, 1/4 cup veggie oil, 1 cup shredded carrot, 1/3 cup honey, and 1 egg. Bake at 350F for 40 minutes. I mixed some lite cream cheese and peanut butter for the icing. Yummyyyy