Some things we've learned: since we were blessed to be able to have our own kitchen in our new Children's Ministry wing, we designed it to be fun and inviting. The walls are bright yellow with huge floor to ceiling fruits, veggies, utensils, etc. painted in bold colors. (Pics are at www.dewittredeemer.org) We spent the extra to purchase a double oven since we bake a lot and in large quantities - it helps when you're in a time crunch. We decided against building an island due to cost and inflexibility. Instead, we use low tables and stools and can re-arrange the room as often as we want. This way, small groups of kids and adults can work together at a table. (We've also moved everything out when we do messy projects for other workshops, such as making mud/straw bricks.)
To help with the need for quick clean-up at the end of the hour, the leaders hand out job cards. Each child gets a card with a task to do - take used utensils over to the sink, put leftover ingredients on the prep table, wipe off the table, etc. This way, everyone pitches in and knows just what they're supposed to do.
Not only is Taste of Heaven a lot of fun, but leaders who aren't comfortable in other workshops find it easy to work with the kids in the kitchen. We also try to make extra, so the kids can take some home to share along with a copy of the recipe - making it readily apparent to parents and older/younger siblings what they did and a good discussion starter at home.