Preheat the oven to 400 degrees F. Grease or line a muffin tin and set aside.
In a large bowl, whisk together the butternut squash, eggs, maple syrup, yogurt, oil, and vanilla. In a small bowl, combine the flour, whole oats, baking powder, salt, and pumpkin pie spice. Add the dry ingredients to the wet ones and whisk or stir together. The batter should be lumpy from the oats.
Use an ice cream scoop or spoon to fill each muffin cup close to the top. Transfer to the oven and bake for 19-23 minutes, or until a toothpick inserted into a muffin comes out clean.
Notes
Ingredients: Canned butternut squash can be found at most grocery stores, but you can use squash that you cook and mash yourself or sub canned pumpkin. Follow my instructions in my post on How to Make Butternut Squash Puree for more info.
Additions: Add ¼-1/2 cup of nuts or chocolate chips to the batter before baking. You can also top the muffins with brown sugar or some extra whole oats before putting them in the oven.
Serving: Enjoy the muffins warm or cold, plain or topped with butter, cream cheese, or nut butter.
Storage: Store at room temp in an airtight container or in the fridge for 3-4 days, or freeze for a few months.