Chocolate sheet cake
Before I start, I'd like to thank you guys for your comments and e-mails. My heart swells!
As my cookbook collection grows, I am realizing how seminal Rose Levy Beranbaum's the Cake Bible is, and deservedly so. Her cakes are some of the most moist and velvety I have ever sampled. One I tried recently is her "Sour Cream Buttercake." The recipe is available on her blog.
Like all her butter cakes, this is an incredibly adaptable recipe. I wanted to take some cake to work, so instead using a springform pan as called for in the recipe, I poured the batter in an 8" x 8" x 2" foil pan.
The baking time was somewhere around 30 minutes, but I rely more on visual cues when altering pan sizes. Butter cakes bake faster at the sides with the middle catching up and doming slightly at some point later. Once this happens, I count eight minutes and then I consider testing the cake with a skewer.
Sheet cakes are incredibly easy. There is only one layer. The frosting does not have to be level, plumb and square at every viewing angle (the hallmark of a fastidiously iced layer cake). Just take some chocolate frosting, pile it on, then take a dinner spoon and swirl the tops.
The resulting dark sea of chocolate will be a sure-fire crowd pleaser.
Here is a good resource for pan size substitutions.
When I tried the recipe in the 8" x 8" x 2" foil pan, the cake rose high and threatened to overflow. In the end, there was enough structure in the cake to prevent it from spilling. However, to be on the safe side, I would recommend just filling the pan to half-full.
On testing with a skewer: if the centre is still jiggly do not proceed with piercing the cake. It is very likely to deflate.