Complex sentence: After working on "The Marvelous Misadventures of Flapjack" and "Adventure Time", the network expressed interest in McHale pitching a pilot to themselves, which became the catalyst for "Garden Wall".
Split into simpler sentences: After working on "The Marvelous Misadventures of Flapjack" and "Adventure Time", the network expressed interest in McHale pitching a pilot. That pilot became the catalyst for "Garden Wall".