A sensor based automated cooking apparatus (2) is provided. A humidity sensor measures the moisture content within a cooking cavity. An output of the sensor is provided to a digital filter (20) to remove noise therefrom before being passed to a feature extraction means (21) which performs a data compression step and extracts salient features relating to the shape of the humidity versus time characteristic. The parameters are analysed by a neural network (22) to estimate a degree of doneness of the food. A controller (24) uses the degree of doneness to estimate the remaining cooking time and appropriate power level. The cooking apparatus (2) then operates in an open loop mode for the remainder of the cooking time using the appropriate power level.