I had some left over batter from a cake I made so I gave it to my mil and she baked it. She left it in the microwave over the weekend and came home and the cake had a funky smell and tasted bad. The only other time I have had this happen was with a cake I made for her. How long can you leave a cake out after it has baked? How long can you leave it out after it is decorated? I have a wedding cake due Saturday and I would feel terrible if it tasted awful! What am I doing wrong?

Breads and cakes need a little air to survive, but not too much. The micro was entirely sealed so that the cake was rotting by the time your mil went to eat it. Three days out is usual, I think. Five days or maybe one or two more in the fridge, but it may pick up odors in the fridge. Fresh is better.

Yuck. I'm sure it absorbed all the smell from the food that's been warmed in the micro also. Good lesson learned.

If you bake and decorating a cake and leave in on the counter for 3 days can it go bad? Have you ever had a cake get a funny crisco taste after a few days ?

Anything already "growing" in that microwave could have attacked the cake too .... mmmm... ewww...

It could have been too humid?

If the cake is due on Saturday, it would be better stored frozen until Friday for decorating. If hot weather, 3days on the counter can be too long for cake. Mold can quickly grow under the icing/fondant cover.