Electrosurgical therapy is provided with an electrode array configured to ablate tissue during insertion of the electrode array into tissue being treated. Once the electrode array is fully inserted, deep heating of the treated tissue can be performed by applying an additional waveform to the tissue with the electrode array. Optionally, the electrical waveform can be varied continuously during insertion of the electrode array to control the extent of coagulation at the side walls and at the bottom of the channels produced by tissue ablation.