Preheat oven to 300 degrees. Lightly grease two 9 inch round cake pans with nonstick spray.
In a bowl cream together butter, salt, brown sugar and vanilla. Add in the baking soda, flour and oats and continue to mix.
Divide the dough in half and press into cake pans, smoothing out so it takes up the entire base of the pan and is smooth on the top. Prick the dough on top with a fork in a pattern if you'd like.
Bake the cakes for 35-40 minutes or until golden brown around the edges. My time is always 37 minutes.
Remove from oven and loosen edges with a butter knife.
Wait 5 minutes then carefully turn cakes upside down to get them out. Immediately after, using a pizza wheel, cut each round cake into 12 pieces.