Prep the oven: Preheat your oven to 350°F (175°C). Line an 8x8-inch square baking pan with parchment paper, leaving some overhang for easy removal.
Melt the chocolate: Place 1 cup chocolate chips in a microwave-safe bowl and heat in 30-second bursts, stirring between each, until smooth. Set aside to cool slightly.
Mix the wet ingredients: In a large bowl, whisk together the nut butter, pumpkin purée, and brown sugar until smooth. Add the eggs and vanilla, whisking until fully combined.
Add chocolate and dry ingredients: Stir the melted chocolate into the pumpkin mixture. Sift in the cocoa powder, pumpkin pie spice, and salt, and fold until no streaks remain.
Fold in extra chocolate: Gently fold in the remaining ½ cup chocolate chips.
Bake: Spread the batter evenly into the prepared pan. Bake for 28–32 minutes, until the edges are set but the center still looks slightly glossy. A toothpick inserted should come out with moist crumbs, not wet batter.
Cool and slice: Allow the brownies to cool completely in the pan before lifting them out with the parchment paper. Slice into squares and enjoy!
