Preheat oven to 350°F. Line an 8 x 8 baking pan with parchment paper, leaving an overhang on the sides to lift the finished blondies out.
Place butter in a small saucepan and set over medium heat. Cook, swirling occasionally for 5-6 minutes, until butter is foamy and fragrant with light brown specks. Remove from heat and immediately transfer to a medium mixing bowl. Set aside to cool slightly.
Mix together flour, pumpkin spice mix, baking powder, cinnamon, and salt. Set aside.
When the butter has cooled a bit, whisk in the egg, then the brown sugar, followed by the pumpkin puree and vanilla.
Slowly add flour mixture to the butter/egg mixture and stir until combined. Fold in the chocolate chips and smooth half the batter into the prepared pan.
To make the ganache, heat cream in a small saucepan until just beginning to bubble around the edges. Place chocolate in a small bowl and immediately pour the hot cream over the chopped chocolate, let sit for 4 minutes. Whisk the cream and the chocolate together until you have a smooth, glossy ganache.
Drizzle ganache over the top of the blondie batter and swirl around. Sprinkle flaky salt and transfer to oven. Bake for 30-35 minutes, or until the edges of the blondies are golden and begin to pull away from the edges of the pan and a skewer inserted into the middle comes out clean. Remove from the oven and allow to cool completely before cutting into squares. Enjoy!
