The batter is the innocent part. A slice of the plain sponge is about 130 calories, flour, egg, sugar and baking soda. Everything after that is the problem. The seller brushes the hot pancake with a thick layer of margarine, 15g per slice, which is 110 calories. Then sugar, then meses, then cheese, then condensed milk. By the time it is folded the slice is 270, and the butter and toppings are more than half.
The count is what gets people. Martabak is sold by the box at Rp 40,000 to 80,000, and a box is 8 slices, 2,100 calories. It arrives at 9pm after dinner, three people share it, and each person eats three slices without noticing, 810 calories. That is a full meal on top of a full meal, and it is why 'martabak night' is the most efficient way to gain weight in Jakarta.
Topping choice moves the number by about 40 a slice. Kacang wijen (peanut sesame) is the lightest of the classics at about 250. Coklat keju is the standard 270. Keju susu with extra condensed milk is about 300. The premium ones with Nutella, Ovomaltine and Kitkat are 350 to 400 a slice, because the spread alone is 100 calories per tablespoon and they use three.
The 'tipis kering' (thin crispy) version is the exception. It is a thin crepe with the same toppings, about 150 calories a piece, and a plate of 6 pieces is about 900. Still not light, but half the thick version by weight of toppings.