Add the 35% Cream to a saucepan and bring it to a boil on low heat.
When it is boiling, add the white vinegar and give a good stir. Let the vinegar act for about 5 minutes, until it curdles – the cream should form clumps, with a solid white part clearly visible, immersed in a slightly yellowish liquid.
Pour the curdled cream into the fine sieve and, with a spoon or silicone spatula, lightly press the mixture to extract as much whey as possible.
Transfer the drained cheese to the blender, and add warm milk, butter, and salt. Beat well until it forms a smooth cream – if necessary, stop beating and scrape the side of the blender with the spatula.
Transfer the requeijão to a glass jar and let it cool completely before covering. Place in the fridge for at least 2 hours to finish firming.