I have been looking to make our doughnut gooey butter cake in individual forms. I finally found the right Flexipan at JB Prince. The mold is 4 inches in diameter and 3/4 of an inch deep. It looks to be the perfect size for us to produce the decadent confection. Ideas in Food: Great Recipes and Why They Work. Maximum Flavor: Recipes That Will Change the Way You Cook. Gluten Free Flour Power: Bringing Your Favorite Foods Back to the Table.