Combine chocolate chips and butter in a large microwave-safe bowl on the Defrost setting for 1 minute. Stir and continue heating in microwave until completely melted, 1 to 2 minutes more.

Fill a 12-inch baking pan with 1 inch of water and place water bath in the oven. Preheat oven to 425 degrees F (220 degrees C). Grease a 9-inch springform pan and line with buttered parchment paper. Wrap the outside of springform pan with aluminum foil.

Set a large bowl over a pot of simmering water over medium-low heat; cook and stir eggs in the large bowl just until warm to the touch. Remove from heat and beat using an electric mixer until triple the volume and soft peaks form, about 5 minutes.

Fold 1/2 of the eggs into chocolate mixture using a rubber spatula until almost incorporated. Fold in the remaining eggs just until blended. Pour mixture into the prepared springform pan. Place springform pan in the water bath in the oven.

Bake in the preheated oven for 5 minutes. Cover pan loosely with aluminum foil and bake 10 minutes more. Cool on a wire rack for 45 minutes. Cover with plastic wrap and refrigerate, 3 hours to overnight.