It's the semi-finals, and the bakers' stress levels are at an all-time high when they face three French pastry challenges and compete for a chance to make it to the final round. This week's Signature Challenge is all about precision as the bakers must make two-dozen Petit Four glacé-style mini cakes. The cakes may be small, but that just makes them that much harder to perfect. Next up, the Technical challenge, which throws the bakers for a loop when Johnny surprises them with a donut – the French Cruller. The bakers won't just need to master their dough; they'll also need to master the deep fryer. Then, in the Showstopper, it's Mille-Feuille, also known as the Napoleon. Layers of perfectly flakey puff pastry sandwiched with unique fillings. But getting it perfect in the short time frame will be difficult for all and the downfall for one.