Preheat oven to 375 degrees. Combine flour, oats, baking soda and salt in a bowl and mix well. Add chocolate chips and chopped pecans or other nuts - mix again.
In a large mixing bowl, beat butter, granulated sugar, brown sugar and vanilla until creamy. Add eggs one at a time, beating well after each addition.
Gradually fold in dry ingredients already mixed separately. Use a cookie scoop for more uniform cookies, drop onto un-greased baking sheets.
Bake for 12-15 minutes, or until golden brown. Cool on baking sheet for 1 minute; remove to wire racks to cool completely.
Tips for storing dough in freezer: Scoop dough onto a cookie sheet, using a cookie scoop, in individual servings, place cookie sheet in the freezer until dough is frozen, then place the servings in a freezer bag. Then when you are ready to bake cookies the next time, remove only the number of servings you want, no need to thaw before baking.
Freezing the dough in individual servings works well before the holidays. You can freeze several batches of dough this way and have ready to give as gifts or pop in the oven on a moments notice for unexpected company.