Preheat oven to 350°F (175°C). Line an 8-inch square baking pan with parchment paper.
Blend wet ingredients: Blend pumpkin puree, cottage cheese, eggs, maple syrup, and vanilla until completely smooth.
Mix dry ingredients: In a bowl, combine rolled oats, protein powder, pumpkin spice, baking powder, baking soda, and salt.
Make the batter: Pour the blended mixture into the dry ingredients and stir just until combined. Fold in pecans or chocolate chips if using. Add a splash of milk if the batter is too thick.
Bake: Spread evenly into the prepared pan and bake for 25–30 minutes, until the center is set and a toothpick comes out with a few moist crumbs.
Cool and slice: Cool completely before cutting into 9 bars. Store in an airtight container in the refrigerator for 4–5 days or freeze for up to 3 months.