Preheat oven to 375ºF, set oven racks to the middle and line a baking sheet with parchment paper or a silicone baking mat.
Whisk together the non dairy milk and flax meal. Set aside.
3 tbsp flax meal
In a medium bowl, whisk together the flour, baking soda, salt and cinnamon powder. Set aside.
Using a stand mixer or a hand held mixer with a large bowl, beat the butter on high until smooth. With the mixer on medium, gradually add the granulated sugar and brown sugar. Beat the butter and sugars on high for about 5 minutes, or until the butter has doubled in volume. Scrape down the sides regularily.
With the mixer on medium, add the plant milk+flax meal mixture and the vanilla extract. Beat the mixture on high for 1 minute or until smooth.
With the mixer on low, gradually add the flour mixture to the wet mixture. Beat on medium-low until a smooth batter forms. Scrape down the sides regularily.
Add the quick oats, walnuts and cranberries to the batter and mix on low until everyting is evenly distributed in the dough.
3 tbsp non dairy milk
To make the cookies, use an ice cream scoop or a ¼ cup measuring spoon to scoop the dough onto the baking sheet(s). Leave about 2 inches of space between each ball of dough. Once you've used up all the cookie dough, flatten each ball of dough with a drinking glass wrapped in plastic wrap so the cookies are about 1 inch thick.
Bake the cookies for 10-15mins. Remove the cookies from the oven and allow them to cool in the tray for at least 10 minutes. At this time the cookies will be very soft and fragile. Transfer them to a cooling rack to cool completely.