Preheat oven to 350F.
Beat the butter with mixer at medium speed until fluffy, gradually add the sugar, beating well. Add the eggs, one at a time. Beat just until blended after each addition. Add the apple, beating just until well blended.
Whisk together the flour, baking soda, cinnamon, cloves, and salt. Add to the butter mixture and mix just until blended. Stir in the walnuts, if desired.
Pour into lightly greased 13 x 9 inch baking pan. Bake 30 to 35 minutes or just until wooden pick inserted in the center comes out clean. Let cool on a wire rack 10 minutes. Serve with Homemade Caramel Sauce and whipped cream, if desired.
Cook the sugar, half and half, butter, and salt in a small saucepan over medium-low heat for 5 to 7 minutes, whisking slowly until thickened. Remove from heat and let cool slightly before serving. Lightly drizzle over individual slices of cake.