The rice cakes are steamed rice flour and water, nothing else, about 36 calories each. Six of them are 215. The reason the plate is 342 is the topping. Chye poh is preserved radish fried in a lot of oil with garlic and a bit of sugar, and a hawker spoon of it holds about 40g, of which a good part is oil. That is about 110 calories on top of the cakes. The chilli adds 17. So one third of a chwee kueh breakfast is the topping.
Some stalls are famous precisely because they are heavy handed with the chye poh and the oil pools on the plate. A plate from one of those is closer to 400 for the same 6 pieces. HealthHub puts a 5 piece plate at about 250, which is a stall with a lighter hand. The cakes are the same everywhere. The topping is the variable.
At S$2 for 6 pieces, this is the cheap breakfast that nobody counts. 342 calories is about the same as a plate of economy bee hoon with egg at 369, with much less protein, only 5g. It is fine as a breakfast. It is a lot as a snack after another meal.