Preheat and Prep: Preheat the oven to 350°F and lightly grease an 8x8-inch baking dish or spray with nonstick spray.
Mix the Wet Ingredients: In a large bowl, whisk together the pumpkin puree, Greek yogurt, milk, maple syrup, eggs, and vanilla until smooth and well combined.
Add the Dry Ingredients: Add the oats, pumpkin pie spice, baking powder, and salt. Stir with a rubber spatula until fully combined and the oats are evenly coated.
Assemble: Pour the mixture into the prepared baking dish and spread into an even layer. Sprinkle the brown sugar evenly over the top, followed by the pecans or pumpkin seeds, if using.
Tip: The batter will seem loose, which is fine. The oats will absorb the liquid while baking.
Bake: Bake for 35-40 minutes until the edges are golden, the top is set, and the center no longer jiggles when the pan is gently shaken.
Tip: The center may feel slightly soft to the touch, it will continue to set as it cools. Let cool for 15 minutes before slicing.
Serve: Cut into 6 squares and serve, or store for later. Top with a dollop of Greek yogurt and a drizzle of maple syrup if desired.
Notes
Make sure to use canned pumpkin puree, not pumpkin pie filling, which has added sugar and spices that will throw off the balance of the recipe.
This bakes well in either an 8x8 or 9x9 baking dish. A 9x9 will produce slightly thinner squares that bake a few minutes faster.
For gluten-free, be sure to use gf whole rolled oats.