If you think baking at altitude is an issue, try making cookies in space.
The frozen chocolate-chip cookie dough (the same cookies that you get at DoubleTree hotels) was tried several times until the astronauts got it right. The done cookie took over two hours to finish at 325 degrees.
This was the first food prepared from raw ingredients in space. This is a step to supply astronauts something other than dehydrated or prepackaged foods. The successfully cooked cookies returned to Earth to see if they are safe to eat.
What recipe took forever for you to get right?