As complicated as a bread baker may seem, there are only three signals involved.
It would be optimal to be able to interface the temperature sensor, however that would require an A/D converter somewhere. Measuring the temperature serves two purposes: monitoring a warm temperature for the rise stages and measuring the baking temperature. In both of these case we can simply set the dwell (percentage of on time) of the oven heating element for the expected need. This is approximately 2% for rise stages, 100% for heating up the oven and 65% for baking.
Therefore, we only have two simple on/off features to control.