1) If in making cakes the gluten is our enemy, why then we don't use "flour without gluten" ?

2) Sometimes, I see on youtube, famous baker mix eggs/sugar with an electrical mixer during 5 min until the batter doubles its volume. Is the reason for that to make enter the air ? As we also use baking powder which will rise the cake, why we want also to make enter the air in the butter ?

3) In most of the muffins they just mixt the ingredients, without beating eggs/sugar during 5 min. Why ?

4) Why and when do we need to mix rigorously, during 5 min or more, eggs/sugar until it doubles its volume ?

This interesting because I actually want to make a cake with lots of interconnected air pockets. My grandmother used (~40 years ago) to make a chocolate cake that had enough air in it that she could pour a chocolate sauce into the cake. I remember wanting a piece when she finished baking the cake and she told me that it would be a while because she still wasn't done yet. I watched as she slowly poured the chocolate sauce (?) onto the cake and let it soak in. After the entire thing cooled the sauce thickened in the cake. The cake looked like a chocolate sponge filled with chocolate.

I, too, am having problems with my Bundt pan cakes. I made a maple walnut cake & ended up with a hole (like a tunnel) all the way around the middle of the cake. Tonight I made the poppyseed cake recipe on the jar of Baker’s filling. I have made this cake in this pan numerous times, & never had any problems, until tonight when I have ended up with the hole in the center of the cake all the way through I am ready to quit baking.

Hi, That's an interesting question: are you saying there are holes in the ganache layer? It could be that you incorporated too much air into it as it was thickening, then the bubbles popped when you poured it on the cake, leaving holes?