Preheat the oven to 350°F (175°C). Line a 9×9-inch baking pan with parchment paper, leaving an overhang on the sides for easy removal.
In a large bowl, whisk together the rolled oats, whole wheat flour, baking soda, ground cinnamon, salt, and ground flaxseed until well combined.
In a separate medium bowl, mix the unsweetened applesauce, honey, melted coconut oil, eggs, and vanilla extract until smooth.
Pour the wet ingredients into the dry ingredients and stir until just combined.
Fold in the dried cranberries and chopped walnuts evenly throughout the batter.
Transfer the batter to the prepared baking pan and spread it out evenly, pressing gently to compact the mixture.
Bake for 22 to 25 minutes, or until the edges are golden brown and a toothpick inserted into the center comes out clean.
Remove the pan from the oven and allow the bars to cool completely in the pan on a wire rack.
Once cooled, use the parchment paper overhang to lift the bars out of the pan and place on a cutting board.
Cut into 12 equal bars.
To freeze, wrap each bar individually in plastic wrap and place them in an airtight freezer-safe container or resealable freezer bag.
To serve, thaw bars at room temperature or warm in the microwave for 20-30 seconds.