Easy Flourless Chocolate Cake

Preheat oven to 325 degrees F (165 degrees C). Grease a 10-inch cake pan with oil.

Combine chocolate butter and sugar in a double boiler over simmering water; cook stirring frequently and scraping down the sides with a rubber spatula until melted and smooth about 5 minutes.

Pour chocolate mixture into the bowl of a stand mixer fitted with the paddle attachment; beat on low speed until cooled about 5 minutes. Increase speed to medium; beat in eggs one at a time. Add water and vanilla extract; beat on low speed until blended. Pour into the prepared pan.

Place cake pan inside a large baking dish. Pour enough water into the baking dish to come halfway up the sides of the cake pan.

Bake cake in the preheated oven until a knife inserted into the center comes out clean about 1 hour. Allow cake to cool in the water bath about 1 hour. Transfer to the refrigerator; chill until firm 8 hours to overnight.