Can I open the oven door during baking?
The oven door may always be opened during baking. Naturally there will be a heat loss in the oven and this will slow down the baking process. In principle, pastries must be baked at the same temperature throughout the entire baking process. Lowering the oven temperature during baking is OK. It is not recommended to increase it. If the oven temperature is increased during the baking process, the pastry will be dry and crumbly.
Very important: when baking bread or pastry, baking is always done in a preheated oven. So the desired baking temperature must be reached before the pastry goes into the oven.