Cream butter and sugar in a mixing BOWL until light and fluffy.
Measure out molasses, buttermilk,, ginger, cinnamon, nutmeg and brandy in a BOWL. Add to creamed sugar and butter. Mix well.
Whisk (or beat) eggs till fluffy in a separate BOWL. Sift flour and cream of tartar in another BOWL.
Add eggs and flour, alternately, to the batter. Keep mixer on low until all the eggs and flour is added. Zest and juice an orange in another BOWL. Don't skimp on the orange. You need every bit of the zest and juice to cuts the richness of molasses. I was fortunate to be able to go out in my backyard and pick a big ol' fresh navel orange. Add juice and zest. Lightly mix.
From here on out, all the mixing is done by hand. Dissolve baking soda in warm water in another small BOWL or cup. Add to batter and mix by hand. Mix raisins with a small amount of flour in another BOWL. This will keep the raisins from sinking to the bottom of the batter (hopefully).
Add flour coated raisins to batter and stir in by hand. Pour into a greased 9x13 pan. Bake at 350 degrees for 40 to 45 minutes or until an inserted toothpick comes out clean. Let cool in pan for 10 to 15 minutes. Turn out on a cooling rack. Cool completely before cutting. Mrs. Washington recommended greasing the pan but didn't say to flour it. I was able to get the gingerbread cake out of the pan without it sticking but I really had to work at it with a rubber spatula. Next time, I will lightly dust the pan with flour.
This cake is better than I ever imagined it would be. It's worth every BOWL that was used. We don't typically put raisins, orange zest and orange juice in gingerbread cake today. I'm not sure why that fell out of favor because this has the best flavor of any gingerbread cake I've ever had. The raisins and orange give it such a nice fruity flavor that it would be a welcomed alternative to fruitcake. Despite mixing them with flour, more of the raisins sunk to the bottom than I would have liked. Sometimes mixing flour with add-ins works better than other times. If I had a dollop of fresh whipped cream, it'd be sitting right on top of a big square of Mrs. Washington's Gingerbread Cake. I'll have to settle for a light sifting of powdered sugar for now.
Fresh Orange Nutmeg Whipped Cream
1 pint whipping cream
2 to 3 tablespoons powdered sugar
1 teaspoon grated orange zest
1 teaspoon vanilla extract
Whip cream until soft peaks form. Mix in powdered sugar (according to your taste) , orange zest and vanilla extract. Grate a small amount of nutmeg on each serving.