Oatmeal Raisin Sheet Cake

This oatmeal raisin sheet cake is the workhorse of bake sales, school events, and church potlucks. Despite the name, there’s no oatmeal in the ingredient list (a quirk worth noting before you start). The cake earns its name from a similar spice profile and texture to a chewy oatmeal-raisin cookie, plus rave reviews from anyone who’s eaten one.

The trick to the moist crumb is the raisin plumping. Simmering raisins in boiling water for ten minutes hydrates them so they don’t pull moisture from the batter as they bake. The cooled raisin water goes into the batter too, lending sweetness and faint raisin flavor throughout the cake.

Cinnamon and cloves are the foundational spices. Half a teaspoon of cloves is bold for a sheet cake, but it works against the raisins and brown sugar to create that distinctive warm-spice flavor profile. Don’t reduce; the cloves should announce themselves.

The icing goes on hot cake, not cool. The heat melts the icing slightly so it spreads thin and even across the surface. Wait too long and the icing becomes a stiff frosting that sits on top instead of integrating into the cake.

Pro Tips

• Spread the batter slightly thinner in the middle than at the edges. Sheet cakes bake more on edges, so this evens out the doneness.
• Use parchment paper to line the sheet pan for easy cake removal and cleanup.
• Cool for 10 minutes before icing if you want a thicker frosting layer; ice immediately after pulling from the oven for a thin glaze finish.

Variations

• Stir in 1 cup chopped walnuts, pecans, or shredded coconut along with the raisins.
• Substitute currants or chopped dates for half the raisins for a more complex dried-fruit profile.
• Add 1 teaspoon ground ginger or allspice for additional warm-spice depth.