Leche Flan (Filipino Baked Custard)

Ingredients for 36 servings

• 7 ounces granulated sugar (1 cup; 200g)
• 12 large egg yolks (8 ounces; 225g)
• One 12-ounce (355ml) can evaporated milk
• Two 14-ounce (800ml) cans sweetened condensed milk
• 1 teaspoon vanilla extract
• 1 teaspoon freshly grated lemon zest from 1 lemon