Preheat your oven to 350°F / 175°C.
Line two large baking sheets with parchment paper.
In a large bowl, cream together the shortening, softened butter, and brown sugar until light and fluffy, about 2-3 minutes.
Beat in the egg and vanilla extract until well combined.
In a separate medium bowl, whisk together the all-purpose flour, baking soda, salt, and ground cinnamon.
Gradually add the dry to the wet , mixing on low speed until just combined.
Do not overmix.
Gently stir in the quick-cooking oats and semisweet chocolate chips with a spatula.
Scoop about 3-4 tablespoons (60 ml / 2 fl oz) of dough for each cookie and roll into a ball approximately 2 inches in diameter.
Place them on the prepared baking sheets, leaving plenty of space between them (about 6 cookies per sheet).
Gently press each dough ball down with a fork to slightly flatten it. Press a few pieces of chopped walnut into the center of each cookie.
Bake for 13–15 minutes, or until the edges are golden brown and the centers are set but still soft.
Let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely. Store in an airtight container.
Do not overbake! For that perfect soft and chewy center, pull the cookies from the oven when the edges are set and golden, but the middle still looks slightly underdone. They will continue to bake on the hot pan.
Using a combination of butter and shortening is key. The butter provides flavor, while the shortening gives the cookies a wonderfully soft, tender texture and helps them hold their shape.
