What I like about the petit entremets is that they are rooted in solid French techniques but much more daring in playing with flavors and textures. Some combination is not commonly seen and the overall sweetness is just right. Since Arcachon is some sort of a "neigbourhood cake shop" (yet so popular that queues form at the shop), prices sit at an average 450-540 yen, which is a very reasonable deal considering the complexity of the cakes. Hence, splurging on cakes from Arcachon is less likely to burst your budget compared to big brand names like Pierre Herme, Sadaharu Aoki or Hidemi Sugino.
Here are some tasting notes of the cakes I've had:
Rose pink
The flavor of rose in the white mascarpone layer is shockingly intense as its pink appearance; but I'm not complaining as I adore the floral tones and thankfully it is paired with tangy raspberry gelee, not lychee. In fact, I think this is even a more successful rose creation than PH's Ispahan. In between the moist genoise is the rose mousse which had an interestingly bouncy texture. 
Fromage
Light and neutral-tasting cheese mousse which did not conflict with the tangy rhubarb. Simplistic as it might seem, I enjoyed the spiced biscuit base which had chunky nuts.
Baba au framboise
I usually stay away from Rum baba as it is very bready but this is not. As the name "Baba", the liquor permeated every possible space of the yeasty bread and made me happily dizzy. I liked how the base is fortified by a milk chocolate spiral, which provided a welcoming contrast in both texture and flavour.
The Ekinokusu エキノクス stirred a moment of dejavu as I had an exactly banana-oolong tea combination from Rue De Passy. Beneath the shiny chocolate glaze is a layer of milk chocolate that rubbed shoulders coherently with the smooth earl grey Creme beurre. However, it was too sweet and I prefer the Trio of Chocolateプールカ , which is more than what the name suggests. Much efforts have been channeled to play up on the aesthetics and flavors with pistachio genoise and crunchy toppings.
Choux CroquanteCrisp, airy shell that hosted vanilla-accented creme patisserie which was tremendously delicious and melty. I'm not surprised actually but not every chef can excel in both cream and choux. This is excellent.
アルカション －ARCACHON－
Tokyo-to, Nerima-ku, Minamioizumi 5-34-4
東京都練馬区南大泉5-34-4
Tues- Sun 10:30am-8pm
Closed on Mondays
Tel: 03-5935-6180
www.arcachon.jp/cakes