To a large bowl add the flour and butter.
Cut the butter into the flour until it is like a coarse meal.
To this mixture add the oats, brown sugar, and baking soda.
Mix well and I use my fingers to really get it well incorporated.
Take out ½ cup of the mixture. Add the nuts to this ½ cup and set aside.
Press the remaining mixture into an ungreased 8x8x2 or 9x9x2 inch baking pan.
I used 8x8x2 but I will tell you the different cooking times at the end during the baking instructions.
Spread your filling evenly all over this layer.
Sprinkle the crumb mixture that you set aside all over this filling mixture.
Spread it out evenly and press, lightly, with your hand.
Bake at 350° for 30 to 35 minutes for a 9x9x2 pan and 35 to 40 minutes for an 8x8x2 pan. The 8x8x2 pan will make your bars a little taller as in my photo.
Let the bars cool completely in the pan.