Line an 8×8 inch pan with parchment paper or plastic wrap and set aside. To help the parchment paper stick, you can spray the pan with cooking spray first.
Blend dates, banana and vanilla in a large food processor for about a minute, or until smooth. Add walnuts, almonds, 3/4 cup of the oats, flaxseed, cinnamon and salt and blend for another minute or two, or until fairly smooth.
Scrape down the sides and add in the other 1/4 cup of oats and protein powder. Process for another minute or until the mixture is well combined. It will be very thick and sticky. Stir in optional chocolate chips.
Spoon mixture into prepared pan. With wet hands, flatten in pan until it looks fairly even throughout.
Place pan in freezer for at least 2-3 hours. Remove from freezer and slice into 10 bars.
Store bars in freezer–they can be eaten directly from the freezer without thawing.