Step 1Heat the oven to 350 degrees. Cream the butter and sugars until light and fluffy. Add the eggs one at a time, beating until blended.
Step 2Add the pears, ginger and vanilla and mix. The mixture may look curdled at this point.
Step 3Sift together the cake flour, baking soda and salt. Add the flour mixture to the pear mixture alternately with the buttermilk, beginning and ending with the flour mixture. Beat until blended, scraping the sides of the bowl as needed. Be careful not to over mix.
Step 4Pour the batter into a greased and floured 9-inch round cake pan with a removable bottom or a springform pan. Bake until a skewer inserted in the middle comes out clean, about 45 to 50 minutes. Cool in the pan for 15 minutes, then remove the cake to a cake plate. Serve with whipped cream and pear slices.