Heat oven to 350°F. In medium bowl, combine powdered sugar and 3/4 cup butter; beat at low speed until crumbly. Add eggs 1 at a time, beating well at medium speed after each addition. Add vanilla; beat well. Add flour, cornmeal and baking powder; mix well.
Place 1/4 cup butter in 9-inch round cake pan. Heat in oven for about 4 minutes or until butter is melted. Sprinkle brown sugar evenly over butter. Arrange pear slices over mixture in pan, slightly overlapping. Spoon and carefully spread cake batter over pears.
Bake at 350°F. for 55 to 65 minutes or until toothpick inserted in center comes out clean. Cool in pan on wire rack for 5 minutes. Invert onto serving plate. Serve warm or cool with whipped cream.