Let the mixture rest in the fridge to allow bubbles to pop, ensuring a smooth texture.
Make the Caramel Sauce
In a medium-sized pan, melt sugar over low heat until it turns a light amber color.
1 cup white sugar, 1/3 cup boiling water
Carefully and slowly add water to the caramel., one tablespoon at a time. It will bubble and some parts may harden, but this is normal. Continue stirring until smooth.
Pour the caramel into a bundt pan, swirling to coat the bottom and sides. Let it cool.
Assemble the Pudim
Preheat the oven to 320°F (160°C).
Pour the custard through a sieve into the caramel-coated bundt pan.
Cover with foil. Place the bundt pan in a roasting pan and place the roasting pan in the oven. Pour hot water into the roasting pan, reaching halfway up the sides of the bundt pan.
Bake
Bake for at least 1 hour and 20 minutes . Do not increase the heat to avoid bubbles.
Your flan is ready when it jiggles without ripples, the top is not wet, and a toothpick inserted comes out clean.
Refrigerate
Let it cool for 30 minutes to 1 hour. Run a knife around the edges before refrigerating.
Chill in the fridge for at least 6 hours, preferably overnight.
Unmold and Serve
Place the bundt pan over hot water or an open flame for about 30 seconds to 1 minute to melt the caramel.
Wiggle the pan to ensure the pudim is loose.
Run a knife around the edges again. Place a large, rimmed plate over the bundt pan and carefully flip it over. Serve and enjoy!
If your caramel ends up a little lumpy do not worry. Little lumps of sugar will usually melt in the oven as the flan bakes. It is more important that you do not burn your caramel trying to melt all the lumps. Next time use low to medium heat to melt the sugar and resist stirring too much. Swirl the pan gently instead.