Cream sugar and butter. Add egg, bananas, honey and milk. Add the combined flour, baking powder, baking soda, salt (like a dash or two) and oatmeal. Stir until blended. Add nuts and raisins. Spoon in greased muffin tins. Bake at 375 degrees for 20 minutes. Yes, you should have preheated it before combining your ingredients.
-I've been experimenting with flour, not in overall quantity, but in proportions. Instead of using just all-purpose flour, I'll use cut that to a smaller proportion and add three tablespoons of rice flour, or buckwheat flour, or whatever flour I find in the cupboard that strikes my fancy (though not corn flour). It doesn't affect much to the consistency or flavor, not in such small proportions, it seems.
-Not all ovens are created equal. Some heat more than their thermostat tell you, or less, some heat more at the bottom than at the top, or at the back than at the front, and so on. Get to know your oven, so that when you read a recipe that says, 'Bake at 375 degrees for 20 minutes', you know that for your oven it translates into 'Bake 375 degrees for 18 minutes in the middle right corner of the oven and rotate the muffin tray halfway through'.
-Sugar is overrated, and over-used. As a rule of thumb, any baking recipe I find (unless it's bread), I will cut the sugar by 20-30%, and everything turns out fine. (Especially in this case where the raisins and/or cranberries add their own sugar) Besides, if a baked good isn't sweet enough, it is easily corrected at the consumption end of the spectrum by eating it with jam or Nutella...