Preheat oven to 375°.
Lightly butter a square (8×8 inch) pan.
In a large mixing bowl, stir together the butter, honey, applesauce, and vanilla.
Add the oats, flour, and baking soda. Beat well until combined. Stir in 1 cup of your choice of add-ins.
Press mixture hard into pan.
Bake for 15-20 minutes until just golden brown on the edges.
Allow to cool for at least 10 minutes before cutting into bars. Let bars cool completely in pan before removing and serving. Store at room temperature or freeze.