Preheat your oven to 350°F (175°C). Line your 9x9 inch baking pan with parchment paper, allowing some overhang for easy removal later.
In a mixing bowl, combine the pitted and halved dates with the apple juice. Use a fork or a potato masher to mash the dates until they form a paste.
In another bowl, whisk together the oat flour, rolled oats, cinnamon, and nutmeg.
To the date-apple juice mixture, add the mashed bananas and vanilla extract. Mix well until everything is combined. Gradually fold in the dry ingredients until just incorporated.
Gently fold in the frozen blueberries and chopped walnuts.
Pour the mixture into the prepared baking pan, spreading it evenly. Bake for about 25-30 minutes, or until the edges are golden brown and a toothpick inserted into the center comes out clean.
Once baked, remove the pan from the oven and let it cool in the pan for about 10 minutes. Use the parchment paper overhang to lift the bars out of the pan and place them on a wire rack to cool completely. Slice into squares or bars and enjoy!
