To begin, preheat your oven to 350 and spray a muffin tin with non-stick spray (or line with cupcake liners).
To a large mixing bowl, add your butter, Greek yogurt, applesauce, maple syrup, pumpkin puree and vanilla and whisk together till smooth. Add your eggs and whisk in briefly.
To the same bowl, add your oat flour, protein powder, pumpkin spice, baking soda, and salt and stir together till you have a smooth, even muffin batter. Add your chocolate chips and fold them into your batter.
Fill each muffin tin 2/3 way full with batter. I like to use a small spatula to round the tops of the muffin batter, prior to baking, for a round muffin top. Alternatively, you could add the muffin batter to your muffin tin with a large cookie scoop or ice cream scoop.
Bake in the oven for 17-20 minutes, or till the tops are springy to touch and a toothpick inserted comes out clean.
Stored in an airtight container in the fridge, these last about a week.
*I've tested these muffins with a whey protein powder and a plant-based protein powder, and I would recommend them both.
*The amount of protein will depend on the type of protein powder used. Each muffin has roughly 3.2 grams of protein, without the protein powder in it. I've found the typical range of protein (with protein powder) is about 6-9 grams each.