Preheat oven to 350 degrees.

Invert bottom of a 9-inch springform pan (this makes it easy for the cake to slide onto a serving platter) Line the pan with a parchment round; spray with non-stick baking spray.

Using a microwave, set to medium power. Place the white chocolate chunks in a microwave-safe dish and heat for 30 seconds at a time, mixing after each stop. When there are a few bits of unmelted white chocolate remaining, continue stirring until all the white chocolate is melted.

Beat together egg yolks and 1/2 cup sugar with a mixer on medium-high speed until thick and pale, about 3 minutes. Add the salt, vanilla, and melted chocolate; beat about 1 minute more. Stir in the white food gel if using

In a separate bowl, beat egg whites on medium-high speed until foamy. Increase speed to high; gradually add remaining 1/2 cup sugar, beating until stiff peaks form, about 5 minutes. Fold beaten eggs into the chocolate mixture in 3 batches. Don’t over mix. It will deflate the batter.

Transfer batter to pan and bake until set, 40 to 45 minutes. Let cake cool completely in pan on a wire rack. Remove side of pan; transfer cake to a serving plate. Serve with the desired topping.