This is an exploratory, single-arm, phase II study designed to assess the anti-tumor activity of a combinatorial regimen consisting of Erlotinib plus Sirolimus among patients with recurrent GBM. The combinatorial regimen of Erlotinib plus Sirolimus is rationally designed to simultaneously inhibit upstream (EGFR) and downstream (mTOR) mediators of Phosphatidylinositide 3-kinase/Protein Kinase B (PI3/AKT) signaling. In a recently completed phase I study, we determined that an EGFR inhibitor (Gefitinib) can be safely combined with Sirolimus at dose levels that are routinely used in the monotherapy setting. Therefore, the primary endpoint of this study is the probability of progression-free survival at 6 months among recurrent GBM patients treated with standard doses of Erlotinib plus Sirolimus. An important secondary objective is to further assess the safety of Erlotinib and Sirolimus for patients with recurrent GBM.