In a small bowl, combine the ground flax and hot water together. Set aside for 3-5 minutes, then vigorously stir until viscous.
Preheat the oven to 350° F.
In a stand mixer or large bowl, combine the remaining ingredients with the flax mixture. Mix on low to medium speed until a dough forms, about 2 minutes. Try not to over-process – the dough should be soft and moist not wet.
Divide the dough in two pieces and place one on a nonstick mat or lightly floured surface. Using a rolling pin, roll the dough out about ¼ inch thick. You can either use cute cookie cutters or cut the dough into squares or rectangles with a knife. Transfer the biscuits to a lined baking sheet. And repeat with remaining dough.
Bake the biscuits until dry and hard - about 25-30 minutes for smaller biscuits and 30-35 minutes for larger biscuits. This completely depends on the size, thickness, and moisture of your biscuits.
Remove from the oven and allow to cool completely before storing in an air-tight container for up to 1 week.****
Notes
* You can substitute with most flours, including oat flour, spelt flour, white whole wheat flour, white flour, rye flour, etc.** If you wish to use fresh homemade pumpkin purée, be sure it’s similar to the consistency of canned pure packed pumpkin, or adjust the amount of plant milk used.*** Be sure to use a natural peanut butter that doesn’t contain any artificial ingredients, especially Xylitol, which can be poisonous to dogs.**** Stores in an air-tight container on the shelf for up to 1 week. You can also store these biscuits in the refrigerator for up to 2 weeks or in the freezer for 1-2 months.