Answer:
the additional benefit from the dessert with the additional cost of the dessert.
Explanation:
According to economics, everyone should act by comparing the marginal benefits obtained by purchasing a good or service vs the marginal cost of obtaining this good or service.
In this case, the customer places a certain value on the utility received from consuming dessert, and if that value is equal or higher to the cost of the dessert, then the consumer will order and eat it. If the perceived value of the benefits received form consuming the dessert are lower than the cost of the dessert, then the consumer will not order it.