Line a 9x13 inch pan with foil or parchment paper. For a half batch, use an 8-inch pan.
Toast the wheat germ by baking at 350 for about 7 minutes or heating in a dry skillet until fragrant.
In a large mixing bowl, preferably a stand mixing bowl but it doesn't have to be, combine the toasted wheat germ with the wheat bran, oats, flour, baking soda, salt, cinnamon and brown sugar. Mix for about 1 minute or until everything is evenly blended.
Add the softened butter to the bran mixture and mix with the paddle until soft and crumbly. Add the egg and vanilla and continue mixing with the paddle until mixture holds together when you pinch it. Mix in the chocolate chips.
Empty the mixture into the foil lined pan. Lay a sheet of parchment or another sheet of foil across the top and press down tightly. You can do it with your hands or use a smaller pan to press down. and cover. Cover and chill overnight or for at least 6 hours.
When ready to bake, preheat the oven to 350 degrees F.
Remove the dough from pan and set it on a cutting board. Cut into large squares. If they break apart, just push them together the best you can. You will shape them more during the bake. Arrange 6 squares on each of two large rimmed baking sheets and bake one sheet at a time.
Bake the first sheet for 12 minutes. Remove from oven. The bars will have puffed up a little, so use the bottom back edge of a spatula to push inward, shaping into neat squares.
Return to the oven and bake for another 2-3 minutes. The bars will still be a little soft when you pull them from the oven, so let cool for about 20 minutes directly on the pan. Carefully transfer to a rack to cool completely.
At this point you can serve them, but they will hold together better if you chill them and let the chocolate set. Bring back to room temperature to serve.
Notes
I've only tested the half batch version as vegan or egg-free. To make vegan or egg-free, use half of all the ingredients and omit the egg. Add ½ teaspoon whole psyllium husks to the dry mixture and replace egg with a mixture of 1 tablespoon of ground flax and 3 tablespoons of water. For the butter, use Earth Balance or another good tasting vegan margarine. Use an 8-inch square pan as a mold.