Line a small container or loaf pan with parchment paper for easy removal.
In a large mixing bowl, whisk together the vegan chocolate protein powder, rolled oats, cocoa powder, chia seeds, and sea salt.
Add the almond butter, maple syrup, vanilla extract, and almond milk to the dry ingredients.
Stir the mixture vigorously until a stiff, cohesive dough forms that holds its shape when pressed.
Fold in the chopped walnuts until evenly distributed throughout the chocolate base.
Transfer the mixture to the prepared pan and press down firmly to create an even layer.
Place the pan in the freezer for 30 minutes to allow the bars to firm up.
Remove from the freezer, lift the parchment paper out, and slice into thick bars.