How to achieve a super leavened cake as the Pierre Herme ones?
Pierre Herme's "Cake Ispahan" is basically a pound cake flavoured with rose, raspberry and litchi, then glazed.

Let's look at the ingredients as reported on PH's own online shop:


Sugar
water
wheat flour (GLUTEN)
EGGS
cream (MILK)
butter (MILK)
freeze-dried raspberries (2,6%),
freeze-dried litchis (2,6%),
hydrogenated vegetal fats (coconut and palm kernel oils)
whole MILK powder
cocoa butter
natural rose flavor (0,6%)
chopped ALMONDS
baking powder (E450I, E500II and corn starch)
emulsifier : GMO-free SOYA lecithin
potato starch
Guérande salt
natural vanilla extract
dyes : cochineal carmine, E129 and E171.


Emphasis mine on the ingredients that are functional to the cake texture and leavening.

The above looks like the product of some serious food engineering. It's a recipe highly tuned to keep cost down, be highly reproducible, keep well for long periods of time, and of course still be delicious.

Now, how do you get a good tasting pound cake with a huge, cartoon looking dome like Herme does, but without the resources (or just the time) to tinker until you find that 0,3% of potato starch is the right amount? luckily you don't have many of the constraints that lead to that recipe: you can increase food cost (since you don't want to make a profit on it), you can tolerate some variability in the product, and it doesn't have to keep as long (we all know it will be gone in two days after baking)

So, here's the key elements to obtain a big dome:


Cream the butter in a stand mixer, and don't stop until it's very fluffy
Keep creaming while you add eggs (adding them slowly and at room temperature helps the stability of the emulsion


or:


Whip eggs in a stand mixer, and don't stop until they're very fluffy
Add oil or melted butters, keep whipping


then:


Use the weakest flour you can find
You can make your flour even weaker by swapping 10% of it with potato starch
Don't skimp on chemical leavening. Don't even think of skipping it entirely.
Either just before putting it in the oven, or as the crust is beginning to form (5-10 minutes), make a cut on the surface lengthwise, to make sure the crust will split there and not make different splits in undesired places
A smaller pan size seems to work better