Preheat the oven to 425°F. Spray 6 - 6-ounce ramekins with nonstick spray. Set them on a baking sheet.
In a medium-sized heat-safe bowl, microwave the white baking chips and cubed butter for 1 minute. Stir well and continue microwaving in 15-second intervals, stirring until the mixture is smooth.
Stir in the flour, sugar, lemon curd, lemon zest, and vanilla extract. Stir just until combined.
Add the eggs and egg yolks, stir until well incorporated,
Evenly divide the cake batter between the ramekins and fill the ramekins 2/3 full.
Bake for 20 to 25 minutes. The tops should be browned and spring back when touched. In my oven, it took the full 25 minutes.
Allow the cakes to rest for 5 minutes.
Carefully run a knife tip around the ramekins’ sides to ensure the cake is not sticking. Place a saucer on top of the ramekin and flip the ramekin over. Allow the dish to rest for just a minute and slowly remove the ramekin.
Dust with powdered sugar if desired.