Preheat the oven to 350F. Line a 8x8 baking dish with parchment paper.
In a medium/large bowl, whisk together the pumpkin, tahini, maple syrup, vanilla, and egg until smooth. Add the cocoa powder, baking powder, and salt and use a rubber spatula to mix until combined. Stir in chocolate chips (if using, or sprinkle them on top).
Transfer to the baking dish and spread out into an even layer (scatter chocolate chips on top, if using).
Bake for 30 minutes or until it feels relatively firm when you gently press it with your fingers. These brownies are naturally very moist and fudgy and are hard to over bake.
Sprinkle the top with flaky salt. Let them cool for at least 30 minutes so they hold together better. You could eat them sooner, but just know they will be a bit messy.