Rhubarb is just beautiful, and it’s a shame to hide it inside of a pie. This rhubarb upside-down cake shows off all it’s beauty right on top, and allows for your own creativity in arranging the pieces. Leave them long like Smitten Kitchen’s version, try a cubic design like real simple food, or get really fancy with an elaborate diamond pattern like this one from The Kitchen McCabe.
Regardless of how you arrange the rhubarb, the cake is a thick buttery slab of awesome that compliments the tart rhubarb beautifully. Think of a pound cake, but with a soft buttery crumb. Then add warm spices like ginger and cardamom.
Spice wise, there are a number of options. The rhubarb plays well with lemon, and a bit of thyme mixed with the rhubarb topping will give you lovely herbal notes. I particularly love cardamom in the cake, but if you don’t have it on hand, go ahead and substitute allspice.
Traditionally, upside down cakes are made in an oven-safe skillet, and you melt and carmelize sugar/butter topping before quickly spooning on the cake and popping it in the oven. While you can do that, this cake also works out wonderfully in a springform pan.