Melt 1 cup of unsalted butter in a medium saucepan over medium heat until fully melted.
Add 1 tablespoon of pumpkin pie spice to the melted butter and cook for about 1 minute, stirring occasionally.
Stir in 1 cup of granulated sugar and 1 cup of packed light brown sugar until well combined.
Add in 1 cup of canned pumpkin and 2 teaspoons of vanilla extract. Mix until fully combined.
Gently sprinkle the dry ingredients over the wet mixture: 2 cups of all-purpose flour, 1 teaspoon of baking powder, and 1/2 teaspoon of kosher salt. Do not stir immediately.
Fold in 1 cup of semisweet chocolate chips and 1 cup of dark chocolate chips using a spatula.
Pour the batter into a greased baking pan.
Bake in a preheated oven at 350°F (177°C) for about 25 to 30 minutes, checking for doneness with a toothpick.
Notes
For best results, ensure your butter is melted but not too hot, and use room temperature eggs. Avoid overmixing once the flour is added. Adjust the amount of chocolate chips according to preference. You can add nuts or dried fruit for variations.