Preheat your oven to 350°F (175°C).
In a large bowl, cream together 2 1/4 cups shortening, 2 1/4 cups sugar, 2 1/4 cups brown sugar, 5 eggs, and 2 1/2 teaspoons vanilla until light and fluffy.
In a separate bowl, sift 4 1/2 cups flour, 2 1/4 teaspoons baking soda, 1 1/8 teaspoons baking powder, and 1 1/8 teaspoons salt.
Gradually add the dry ingredients to the creamed mixture and stir until just combined.
Fold in 4 1/2 cups old fashioned oats, 1 (12 ounce) bag chocolate chips, and 1 cup chopped pecans.
Use an ice cream scoop to portion dough onto ungreased cookie sheets.
Bake for 20 minutes, until edges are golden brown and centers are slightly soft.
Allow cookies to cool on the baking sheet for a few minutes before transferring to a wire rack.
Serve and enjoy your hearty cowboy cookies!