Combine the pumpkin puree, nut butter, oil, pumpkin pie spice, cinnamon, salt, vanilla, maple syrup, oats, ground flaxseed, and protein powder in a large bowl and stir until combined.
Line a loaf pan with parchment paper and spread the pumpkin base into the pan. Press the contents down evenly into the pan. Place into the fridge to chill while you prepare the chocolate topping.
Add the chocolate chips to a small bowl and microwave in 30-second increments, stirring in between, until the chocolate is melted. Once melted, pour over the pumpkin base and spread evenly.
Optionally, you can add sprinkles or chopped nuts on top while the chocolate is still melted.
Place into the freezer to set, about 15 minutes. Remove from the freezer and remove protein bars from the pan by lifting the parchment paper.
Cut into 7 bars with a sharp knife on a safe cutting surface. Make the cuts as equally spaced as you can.
Enjoy with a cup of tea or coffee.
Notes
Please note that the nutrition data given here is a ballpark figure. Exact data is not possible.