A method of manufacturing a fibre-reinforced spar cap for a wind turbine blade, the method comprising the steps of: providing a spar cap mould, arranging a plurality of pultruded fibre plates in the spar cap mould to form a stacked arrangement of pultruded fibre plates, wherein the stacked arrangement comprises a first lateral surface and an opposing second lateral surface, arranging a first insert member next to the first lateral surface of the stacked arrangement, wherein the first insert member comprises a connecting surface, and wherein the first insert member is arranged such that its connecting surface abuts against the first lateral surface of the stacked arrangement, optionally arranging a second insert member next to the second lateral surface of the stacked arrangement wherein the second insert member comprises a connecting surface, and wherein the second insert member is arranged such that its connecting surface abuts against the second lateral surface of the stacked arrangement, placing a vacuum foil over the stacked arrangement and the first insert member and the optional second insert member, infusing resin into the stacked arrangement and the first insert member and the optional second insert member, curing the resin to join the stacked arrangement and the first insert member and the optional second insert member to form the fibre-reinforced spar cap or a preform thereof, removing the vacuum foil, and demoulding the fibre-reinforced spar cap or the preform thereof from the spar cap mould, trimming or grinding at least part of the first insert member and/or at least part of the second insert member of the preform to form the fibre-reinforced spar cap. providing a spar cap mould, arranging a plurality of pultruded fibre plates in the spar cap mould to form a stacked arrangement of pultruded fibre plates, wherein the stacked arrangement comprises a first lateral surface and an opposing second lateral surface, arranging a first insert member next to the first lateral surface of the stacked arrangement, wherein the first insert member comprises a connecting surface, and wherein the first insert member is arranged such that its connecting surface abuts against the first lateral surface of the stacked arrangement, optionally arranging a second insert member next to the second lateral surface of the stacked arrangement wherein the second insert member comprises a connecting surface, and wherein the second insert member is arranged such that its connecting surface abuts against the second lateral surface of the stacked arrangement, placing a vacuum foil over the stacked arrangement and the first insert member and the optional second insert member, infusing resin into the stacked arrangement and the first insert member and the optional second insert member, curing the resin to join the stacked arrangement and the first insert member and the optional second insert member to form the fibre-reinforced spar cap or a preform thereof, removing the vacuum foil, and demoulding the fibre-reinforced spar cap or the preform thereof from the spar cap mould, trimming or grinding at least part of the first insert member and/or at least part of the second insert member of the preform to form the fibre-reinforced spar cap.