Preheat the oven to 325ºF. (162ºC)
Measure the unbleached flour, whole-wheat flour, wheat germ, and baking powder into a mixing bowl. Whisk until combined.
Combine the peanut butter, carrot, and water in a glass measuring cup. Stir with a fork until smooth and creamy.
Make a well in the flour, and pour in the peanut butter mixture. Mix on medium speed using a paddle attachment until combined.
Turn the dough out onto a slightly floured surface and gently knead until dough is smooth and still soft. Roll dough ¼-inch thick and cut biscuits into desired shapes with cookie cutters.
Place biscuits on a parchment-lined cookie sheet and bake 12– 15 minutes until dry and firm to the touch. Turn the oven off and leave biscuits in another 20– 30 minutes. Remove them from the oven, cool them on a baking rack, and store them in a cookie tin.