I later found a plain cake recipe (White Cake, page 142, from Donna Washburn and Heather Butt’s 125 Best Gluten-Free Recipes) that I thought would be a good jumping-off point for converting it to a decent GF version.
Here's the GF White Cake recipe:
2/3 cup white rice flour
1/2 cup tapioca starch
1/3 cup cornstarch
3/4 tsp xanthan gum
1 1/2 tsp GF baking powder
1/2 tsp salt
1/2 cup shortening or butter, softened
3/4 cup granulated sugar
3 eggs
3/4 tsp vanilla extract
1 tsp cider vinegar
1/2 cup milk
1. Preheat oven to 350°F, and grease an 8-inch (2 L) square pan.
2. In a large bowl, sift rice flour, tapioca starch, cornstarch, xanthan gum, baking powder, and salt. Resift and set aside.
3. In a separate bowl, using an electric mixer, cream shortening and sugar until light and fluffy. Add eggs, one at a time, beating well after each addition. Stir in vanilla extract and vinegar. Stir in dry ingredients alternately with milk, making three additions of dry ingredients and two of milk. Stir just until combined after each addition. Spoon into prepared pan. Spread to edges and smooth top with a moist rubber spatula. Let stand for 30 minutes.
4. Bake in preheated oven for 35 to 40 minutes or until a cake tester inserted in the centre comes out clean. Let cool in the pan on a rack for 10 minutes. Remove from pan and let cool completely on rack.
I blended the two recipes, trying to keep the base of the White Cake, with the flavourings of the Ginger Cake.
Here's my GF Ginger Cake recipe:
2/3 cup white rice flour
1/2 cup tapioca starch
1/3 cup cornstarch
3/4 tsp xanthan gum
1 1/2 tsp GF baking powder
1/4 tsp cinnamon
1/4 tsp ground cloves
1/8 tsp ground black pepper
1/2 cup granulated sugar
3 eggs
1/2 cup oil
1/2 cup molasses
2 tbsp fresh ginger, finely minced
1 tsp cider vinegar
1/4 cup water
1. Oil and sugar 8 rings, 8 ramekins, or an 8-inch (2 L) baking dish.
2. In a large bowl, sift rice flour, tapioca starch, cornstarch, xanthan gum, baking powder, cinnamon, cloves, and pepper. Resift and set aside.
3. In a separate bowl, using an electric mixer, whisk together sugar, eggs, oil, molasses, ginger, and vinegar. While mixer is running, add water.
4. With a large rubber spatula, gently fold in the contents of the mixer with the dry ingredients.
5. Fill rings, ramekins, or dish. Spread to edges and smooth top with a moist rubber spatula. Let stand for 30 minutes. Preheat oven to 350°F.
6. Bake in preheated oven for 35 to 40 minutes or until a cake tester inserted in the centre comes out clean. Let cool in the pan on a rack for 10 minutes. Remove from pan and let cool completely on rack.
I baked it for 35 minutes, then 10 more, then 10 more... The cake ended up baking for 85 minutes, and toothpicks still weren't coming out clean. But by that time, the edges were turning very dark, so I had to take it out. The bottom and edges were on the verge of being burned, but the inside of the cake was still gooey and undercooked.
So, does anyone have any ideas how to fix the recipe? Do I take out some of the liquid? Use more baking powder? And how much?
(Also, the cake was very dense and heavy. Next time I make it, I'm going to whip the egg whites into stiff peaks, then gently fold it in. This may lighten up the texture.)