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 . <EOS>