That Mr bird has a lot to answer for.
Real custard is cream and eggs.
Beat the eggs and mix in the cream, place in a microwave and warm up the mixture gently, whisking between short burst of medium power heating. The mixture will thicken once it gets warm enough.
You can use single cream or thicker ones diluted with water, and the number of eggs is rather dependant upon size and the thickness of the custard required. You can even use milk - but why anyone would want to......
Once made allow to cool down. Add various flavourings. The standard one is vanilla, but be adventurous and try various options - orange flavour with orange jelly, and whipped cream on top with dark chocolate finely grated - or use coconut milk to dilute a thick cream for the custard, then put it on top of a lime jelly with wafer thin slices of lime added at the hot stage to soften and release the oils, decorate with a mixture of whipped cream and desiccated coconut, and then a light sprinkle of more of the coconut. The grated chocolate is also good with a strawberry jelly, with frozen strawberries added in, then add strawberry flavour to the custard and maybe make it pink too - decorate with cream, and maybe fresh strawberries half dipped into melted chocolate.
You can see why my low carb desserts are becoming a much requested item at the various gatherings I attend.