Yes you can.
>If a player chooses to buy only one Casteliacone in Pokémon Black 2 and White 2, the player cannot buy any additional (even though the option for one dozen was previously available) until the next day. Additionally, the player can now purchase the treat in the winter months, unlike in the previous games. -Bulbapedia
But the cone has diminished in popularity, so now unfortunately you can only buy one or one dozen each day, at least until you defeat the champion.
