Preheat the oven to 350 degrees F. Line a baking pan with parchment paper, or a baking matt, or lightly grease it.
In a large bowl add the butter, shortening, sugar, and brown sugar with an electric mix beat until creamy.
Add the egg and mix until well combined. Add the vanilla and mix in.
In a medium bowl sift together the flour, old fashion oats, baking soda, and salt.
Gradually add the flour mixture to the cookie dough, and mix until all is incorporated.
Add the chocolate chips and chopped walnuts and mix in by hand or a wooden spoon.
Drop by heaping teaspoons on the prepared baking sheet.
Bake in the preheated oven for 12 to 14 minutes. Remove the pan and set on a cooling rack for a minute or two. Remove cookies from baking sheet and cool completely on a cooling rack.