Preheat oven to 350°F (175°C). Line 2 baking trays with parchment paper.
In a large bowl, cream the butter, sugar, and salt using an electric mixer for 1–2 minutes until light and fluffy.
Add the oil, maple syrup, vanilla, and prepared flax egg. Mix on low until just combined.
Sift in the flour, baking soda, and cinnamon. Mix until mostly combined.
Fold in the oats, cranberries, and walnuts. Dough should be thick but scoopable. If it feels dry, let it rest 5 minutes or add a tiny splash of soy milk.
Use a cookie scoop (1.5 tbsp) to portion dough. Place on tray 2 inches apart and gently flatten each ball with the back of a spoon into a thick disc.
Bake for 11–13 minutes until the edges are golden and the centers look just set.
Let cool on the tray for 10 minutes before transferring to a wire rack to cool completely.