Preheat oven to 425 degrees. Add muffin liners to muffin pan and spray with a nonstick spray.
In a large bowl mix together flour, oats, baking powder, and salt.
Mix all of the wet ingredients with the sugar: eggs, buttermilk, oil, ripe and mashed bananas and vanilla. (I use an immersion blender to make sure the bananas are well incorporated but you can also use a whisk or even a blender.)
Fold the wet ingredients into the dry using a spatula. Stir in the walnuts and dates. Scoop this into the prepared muffin tins (a little over 3/4 full for large muffins).
Bake for 5 minutes at 425 degrees then change the temp to 375 and bake for 15-18 minutes. Cool in muffin tray for 5-10 minutes. Serve with butter and honey.
For mini muffins bake at 425 for 3 minutes then 375 for 8-10 minutes (this makes 48 mini muffins).