1 Preheat oven to 350F degrees. Cut parchment or wax paper to fit 2 large baking sheets that will fit side by side in oven.
2 Pour all of the dry ingredients except the milk into a large mixing bowl and combine well with a fork. Stir in the milk and mix well. You will now have a wet dough.
3 Place one of the cut pieces of parchment or wax paper on your work surface and use your hands to flatten 1/4 of the dough on the paper. Cover with plastic wrap and use a rolling pin to completely flatten the dough. It may be so thin in some places that you can see through it. Remove the plastic wrap and transfer the bran flake -covered paper onto the baking sheet.
4 Repeat the process with the second piece of parchment or wax paper and another 1/4 of the dough. Bake the 2 sheets of dough for 5 minutes and then check--you want your giant bran flakes to have the consistency of a large cracker. Continue baking until the flakes have the right crispness, checking every couple minutes so you don't burn them.
5 Let the completed flakes cool completely on the baking sheets.
6 Repeat the process with the rest of the dough.
7 Reduce the oven temperature to 275F degree. Tear or break your giant flakes into normal cereal-size pieces and spread them out over the paper-covered baking sheets. Bake for 20 minutes, stirring the flakes every 5 minutes.