Preheat your oven to 350°F (175°C) and line baking sheets with parchment paper.
In a large mixing bowl, beat the softened butter, granulated sugar, and brown sugar together until creamy and well combined.
Add the eggs one at a time, mixing until fully incorporated. Then, stir in the vanilla extract.
In another bowl, combine the rolled oats, all-purpose flour, baking soda, and salt. Gradually add this dry mixture to the wet ingredients, stirring until just combined.
Fold in the chocolate candies and nuts (if using) until evenly distributed throughout the dough.
Using a cookie scoop or a tablespoon, drop rounded balls of dough onto the prepared baking sheets, leaving space between each cookie to allow for spreading.
Bake the cookies in the preheated oven for 10-12 minutes, or until the edges are lightly golden and the centers are set.
Remove the cookies from the oven and let them cool on the baking sheets for 5 minutes before transferring them to a wire cooling rack to cool completely.