01 -
Preheat oven to 350°F (177°C). Grease a standard pie plate or 9-inch springform pan with nonstick spray or butter.
02 -
In a heat-safe bowl, melt butter and 2 cups of chocolate chips using a double boiler or microwave at 50% power in 30-second intervals, stirring until smooth. Allow mixture to cool to room temperature.
03 -
In a stand mixer or with a handheld electric mixer, beat eggs, granulated sugar, and vanilla extract on medium-high speed until mixture becomes pale and fluffy, about 3 minutes.
04 -
With the mixer on low speed, blend in the cooled chocolate mixture until fully combined.
05 -
Gently fold in all-purpose flour, baking powder, and salt just until no streaks of flour remain. Incorporate the remaining 1 cup chocolate chips by hand.
06 -
Transfer the batter to the prepared pan and spread evenly. Bake for 35 to 40 minutes or until the center is puffed and the surface shows cracking.
07 -
Remove pan from oven and allow to cool completely on a wire rack. Slice and serve topped with hot fudge if desired.