For Topping: Combine melted butter, brown sugar and corn syrup in a 9-inch round cake pan. Sprinkle with walnuts. Arrange apple slices over topping.
For Batter: Combine 3/4 cup flour, sugar, undissolved yeast and salt in a large bowl. Heat milk, water, butter and oil until very warm (120° to 130°F). Add to flour mixture; beat 2 minutes until well blended. Beat in eggs and 1/2 cup flour. Mix in remaining flour until smooth. Spoon batter over apples in prepared pan.
Cover and let rise in warm place 45 minutes to 1 hour.
Bake in preheated 375°F oven for 30 minutes or until golden brown. Cool 15 minutes in pan; invert onto serving plate. Serve warm.
