A method of manufacturing an aerodynamic shell part for a wind turbine blade is described. The aerodynamic she part comprises a recess for arrangement and connection of a spar cap within said recess. The method comprising the steps of: a) providing a first mold part having a first forming surface that defines a part of an exterior of the aerodynamic shell part, b) laying up fiber-reinforcement material and optionally also sandwich core material in the first mold on the first forming surface, c) arranging one or more inserts having an exterior shape corresponding to at least sides of the recess of the aerodynamic shell part, d) supplying resin to said fiber-reinforcement material and optional sandwich core material, e) curing or preconsolidating the resin, and f) removing the one or more inserts.