All your life you’ve been told to avoid big white vans where grown-ups offer you candy.

And yet when the Buttercream Cupcake Truck rolls into any given neighborhood, kids of all ages throw caution to the wind and hop in line, mouths watering.

The concept is simple: an old mail truck converted into a rolling cupcake shop (à la your traditional ice cream truck) that makes five stops a week to predetermined locations across Philadelphia.

Through Buttercream’s website and Twitter, Kate Carrara (aka Cupcake Lady) is able to alert cupcake fans to the truck’s daily destinations.

According to Buttercream’s FAQs, the cupcakes are baked ahead of time at Philly Kitchen Share, frosted, sealed in “Cupcake Courier” containers and kept in a freezer until served.

If you are lucky enough to have the Buttercream Cupcake Truck pull into your neighborhood, you can expect an exciting variety of flavors, ranging from staples like vanilla and chocolate to seasonal favorites like pumpkin and apple streusel.

A former attorney, Carrara left law and switched to baking with much success. Combining her own intuition with recipes from friends, family members and cookbooks, running this small company has been an adventure.

As she describes in a video interview and Twitter, “I love that I can…play with the flavors, play with the looks, and they’re just so darn cute. It makes me happy.”

Rather than waiting years to see results in her cases as a lawyer, Carrara finds fulfillment in seeing a tangible product of her labor as well as the smiles her baked goods bring to faces of all ages, all over the city.

Even when the truck breaks down (which, alas, has happened), cupcakes are still baked and delivered. During the truck’s most recent mechanical trouble, the Buttercream folks made free drop offs along with their scheduled special orders.

Single cupcakes are $2 and customers are only allowed up to 6 cupcakes at a time (as we are always told in elementary school, “leave some for the rest of the class”).

The next time you are planning an event, keep in mind that Buttercream accepts special cupcake orders over the phone (267-505-7486) or you can rent the truck for $125 an hour and $1.50 per cupcake.

If you want to see what all of the hype is about, visit the Buttercream website or follow updates on Twitter.