In a medium bowl, combine oat flour, vegan protein powder, and salt.
Add peanut butter, maple syrup, plant milk, and vanilla to the bowl and mix until a thick dough forms. If it seems too dry, add a bit more plant milk (1 tsp at a time).
Fold in the mini chocolate chips.
Press the dough evenly into a parchment-lined 8x4 inch loaf pan.
Optional topping: Melt ½ cup vegan chocolate chips with 1 tsp coconut oil. (Can be done in the microwave.) Spread chocolate sauce evenly over dough.
Refrigerate 1-2 hours until firm. Remove from the refrigerator and cut into 8 bars.
These keep in an airtight container in the fridge for up to 1 week, or in the freezer for up to two months.