Heat oven to 350. Heat margarine in round pan, 9x1 1/2 inches, in oven until melted. Sprinkle with brown sugar. Place 1 pineapple ring in center of pan. Cut remining slices in half; arrange halves cut side out, around pineapple in center. Place 7 maraschino cherries in center or curves of pineapple ringes, if desired. Arrange 6 pecan halves around center slice, if desired.
Beat remaining ingrediants on low speed, scraping the sides of the bowl constantly, for 30 seconds. Beat on medium speed, scraping sides occasionally, for 4 minutes. Pour over fruit in pan.
Bake until wooden toothpick inserted in the center of the cake comes out clean, about 35-40 minutes. Immediately invert cake on a heatproof serving plate. Let pan remain a few minutes. Serve warm.