Combine 1/2 cup butter, brown sugar, hazelnuts and ginger; spread into pan. Arrange pear slices over mixture.
Beat remaining 1/2 cup butter at medium speed with an electric mixer until creamy; gradually add 1/2 cup sugar, beating well. Beat in egg and corn syrup.
Combine flour and next 4 ingredients. Add to butter mixture alternately with boiling water, beginning and ending with flour mixture. Beat at low speed until blended after each addition. Pour over pear slices.
Bake at 350 degrees for 35 to 40 minutes or until a wooden toothpick inserted in center comes out clean. Run a knife around edge of cake to loosen; cool in pan on a wire rack for 10 minutes. Invert onto a serving plate. Remove any foil before serving.