In a bowl, cream butter and Splenda Stevia Sweetener until fluffy. Beat in eggs, vanilla, buttermilk and molasses.
In another bowl, combine flour, oats, baking soda, baking powder, and salt. Add the buttermilk mixture to flour mixture. Then add mashed banana and stir until just mixed.
Scoop batter into lined muffin tray and bake 25 minutes or until a toothpick comes out clean.