According to the Mayo Clinic, hazelnuts are somewhat more fatty than almonds, per ounce by weight (the range is for whether they are roasted or not):
- Almonds - 14 - 15 g
- Hazelnuts - 17 - 17.7 g
As might be expected, hazelnuts are slightly lower in starch. These is unlikely to make any practical difference in the recipe, as both are fairly close.
You should be able to use them close to interchangeably in recipes, although their flavors will be deliciously different, of course.
As for peeling hazelnuts, there are many methods. One of the more effective techniques, which will work if you are going to toast them lightly afterwards is to blanch them in a baking soda solution. See, for example, this article from My Baking Addiction with a video of Alice Medrich and Julia Child embedded demonstrating the technique.
There is no good formula to calculate the time needed for baking custards. It depends on way too many variables, most of which you cannot know, and the calculations would be way too complicated too (a system of differential equations, IIRC). So the sensible way to go is to monitor when it is done and remove it exactly then, not to try to predict the time.
The easiest way to monitor it is by using a thermometer. Without flour, you aim for 83 Celsius final temperature. With flour, it is something higher, maybe 90 Celsius, it will depend a bit on the proportions. Simply stick a roast thermometer into it and bake until it's there, then remove from the oven.
As for the temperature of the oven setting, the lower you can go for a custard, the better. Depends on your patience. I've made creme caramel at 120 Celsius, took close to 3 hours, but the result was great. Setting it around 150 is more common, no matter the amount you are baking. But try not bake a single very deep dish, either make it flat and wide, or use multiple dishes.
Best Answer
Yes, you can use all sorts of pans for chiffon cake and it works just fine. I've made many chiffon cakes and I've never actually used a tube pan as I don't own one!
Turning the cake over is absolutely essential, and you can turn just about any pan over as long as it has a fixed bottom or one that locks into place like a springform pan. Don't use a pan with a loose slide-in bottom because it won't hold the back of the cake up when you turn it over, and it will collapse. Fixed bottom pans can work, getting the cake unstuck from the bottom is tricky though, I use a skewer bent 90° to get underneath stuck cakes, but a springform pan is ideal as you can just use a knife.
You need to make sure that the pan is going to be taller than the cake, or that whatever you sit the rim on will not touch the cake, only the pan's rim. Chiffon cakes rise a whole lot, figure on it rising at least 3 times the batter height. Plan ahead and have it all set up for when you take it out of the oven before you start baking, you don't want to be improvising when you take it out of the oven, seconds matter with chiffon cake.
You need the cake so stick to the pan, so don't butter or flour the pan sides or bottom, or use baking paper. If it doesn't stick it will fall out when you turn the pan over, and that means it will be dense. Chiffon batter will stick to anything, so don't worry if you have non-stick pans.
Enjoy your cake, chiffons are tricky at first but they are great when they come out well!