Preheat your oven to 180°C (350°F).

In a medium pot over medium heat, melt 200g of granulated sugar without stirring, until it turns a beautiful amber color. Pour the caramel into an 8-inch cake tin and let it set.

Combine 6 large egg yolks, 320g of condensed milk, 350ml of evaporated milk, 2 teaspoons of vanilla extract, and 1/8 teaspoon of salt in a large mixing bowl. Whisk until smooth and strain through a fine-mesh sieve over the caramel in the tin.

In a separate bowl, whip 3 large egg whites with 1/4 teaspoon of cream of tartar using an electric mixer until foamy. Gradually add 60g of sugar and beat until stiff peaks form.

In another bowl, whisk together 3 large egg yolks and 60g of sugar until pale. Mix in 40ml of vegetable oil, 50ml of cold water, and 1 tablespoon of ube extract. Gradually add 100g of plain flour, 1/2 teaspoon of baking powder, and 1/8 teaspoon of salt until smooth.

Gently fold the whipped egg whites into the cake batter and pour over the flan mixture in the cake tin.

Place the cake tin in a larger baking dish, pour hot water around it, and bake for 55-60 minutes, until a toothpick comes out clean.

Let the cake cool to room temperature, then refrigerate for at least 6 hours or overnight before serving.