Preheat oven to 350 degrees. Melt butter and blend in sugar. Beat in eggs, 1 at a time. Add flour, salt and almond extract. Mix well. Pour batter into a large iron skillet which has been lined with aluminum foil. (Leave excess foil over sides of pan for easy removal.) Cover top with slivered almonds and sprinkle with sugar. Bake 30-40 minutes.