Preheat the oven to 350°F. Line a baking sheet with a silicone mat or parchment paper.
Place the flour, oat bran, ground flaxseed, and baking powder in a medium bowl. Stir or whisk to combine.
Place the pumpkin puree, egg, and coconut oil in a separate large bowl. Stir until well combined.
Add the flour mixture to the wet mixture and stir to combine until a rollable dough forms.
Roll out the dough onto a lightly floured surface until about 1/4" - 1/3" thick.
Using a cookie cutter, cut out shapes. Place the cutouts on the prepared baking sheet. Gather scraps and reroll until the dough is used up.
Bake for 14-16 minutes. Transfer the treats to a wire rack to cool completely.
Store leftovers in an airtight container.