Adjust the oven rack to the middle position and pre-heat the oven to 375 F degrees. Line 2 baking sheets (if baking them all together) with parchment paper.
In a medium bowl mix flour, baking powder, baking soda, table salt and cinnamon.
In a separate bowl, stir together oats, walnuts, cranberries and chocolate.
In a standing mixer fitted with a paddle attachment, mix the butter and sugar about a minute on medium speed, scraping down the bowl as necessary.
Add the egg and vanilla and continue to mix until fully incorporated for 30 seconds.
Scrape down the bowl to ensure that there are no lumps remaining.
Decrease the speed to low. Add the flour mixture and mix until just combined, 30 to 45 seconds. Do not overbeat.
With the speed on low, gradually add the oat mixture and mix until just combined.
In order to ensure that the ingredients are evenly distributed, give the dough a final hand stir.
Divide the dough into 16 portions and roll them into balls. Stagger 8 balls on each baking sheet by spacing them 11/2 inches apart from each other. Using your fingers, press gently on each dough ball to a 1-inch thickness.
Bake each sheet separately for 15 minutes, rotating halfway through the baking time.
Keep cookies on the baking sheet for 5 minutes and then transfer them to a wire rack (to stop the cooking)
Continue the same process with the second batch.