In a medium bowl, stir together the flour, 3/4 cup of sugar, baking powder, salt, cinnamon and cloves. Cut in the shortening until it is in very small pieces, then mix in the milk and egg using an electric mixer on low speed. Mix for about 1 minute, scraping the bottom of the bowl at least once to avoid lumps. Stir in walnuts by hand. Pour into the prepared pan, and spread evenly.