Cream the butter and brown sugar with a Hand Mixer, until light and fluffy. About 5 minutes.
Add the flour, baking soda and salt. Mix.
Add the oats and mix well.
It will be a crumbly mixture but it will press together.
Sprinkle half the dough into the prepared baking pan.
Press down with your fingers to an even layer all across the pan bottom.
Now take the date mixture and dab teaspoons full here and there across the bottom layer in the pan. It will be easier to spread this way.
With your fingers - gently press out the filling for a solid layer across the complete bottom of the crust.
Sprinkle the rest of the dough over the filling layer.
Make sure it is even. Then press the top crust with your hand to make a solid layer. I use my fingers and the palm of my hand. It doesn't take much pressure.
Bake at 375 degrees for 25 minutes.
Cut into squares while it is still warm.
Cut to make 4 squares across and 6 squares down and that will be 24 bars.