Since, we need the cookies to be 2 cookies for each student and there are 23 students, the total number of cookies needed is 23 x 2 = 46.
Given that 12 cookies has already been baked, let x be the additional number of cookies needed to be baked, then 12 + x = 46
12 + x = 46
x = 46 - 12 = 34
Therefore, the additional number of cookies needed to be baked is 34 coolies.