Melt butter, add sugars, and blend well by hand (no mixer). Add beaten eggs, stir well. Add flour and stir until all lumps are gone. Add pecans and vanilla.
Pour into a greased and floured 9 x 13 baking dish.
Bake approximately 40 to 50 minutes being cautious not to over cook. You want them to remain chewy, hence the name! Cut upon cooling.