Drain pineapple, reserving 1/4 cup juice. Mix pineapple, pecans, 1 tablespoon lemon juice, 1 3/4 teaspoons Equal For Recipes or 6 packets Equal sweetener or 1/4 cup Equal Spoonful and cornstarch in bottom of 8-inch square or 9-inch round cake pan, spread mixture evenly in pan.
In a medium bowl, beat margarine and 3 1/2 teaspoons Equal For Recipes or 12 packets Equal sweetener or 1/2 cup Equal Spoonful until fluffy, then beat in egg.
Combine flour, baking powder, baking soda and spices in small bowl. Add to margarine mixture alternating with buttermilk, 1/4 cup reserved pineapple juice and remaining 1 tablespoon lemon juice, beginning and ending with dry ingredients. Spread batter over pineapple mixture in cake pan.
Bake in preheated 350 degree oven until browned and toothpick inserted in center comes out clean (about 25 minutes). Invert cake immediately onto serving plate. Serve warm or at room temperature.