Deep Dive
The Inspiration and the Technique
Fallow opens by describing his first encounter with this chip at the Dorchester, where Thomas Keller serves it as part of his restaurant's repertoire. The dish blends two classical French techniques: the thousand-layer potato (pommes Anna, or pommana) and the Pont Neuf, the original French fry that was street food on a Parisian bridge. Keller's version takes the thousand-layer concept and cuts it into chip-sized portions before frying. The foundation is Agria potatoes—chosen for their starch content and texture. Fallow emphasizes that peeling is optional for appearance but crucial is not washing them afterward, as the starch on the skin binds the layers together during cooking and frying.
Building and Cooking the Terrine
After peeling, the potatoes are sliced lengthwise on a mandolin to roughly translucent thickness—thin enough to see your finger through them. Fallow cuts lengthwise (not crosswise) to give the terrine structural integrity. The slices are layered into a lined terrine mold with a mixture of 50% beef fat and 50% clarified butter, plus a light dusting of cornstarch between layers to act as an additional binder. He's meticulous about not over-applying cornstarch, noting that too much creates a gummy texture. Once the potatoes are layered, the mold is covered with parchment and a light weight (not heavy—just enough to keep the top from over-caramelizing). It bakes at 140°C for roughly 3 hours. This long, gentle cook is non-negotiable: too hot and the outside caramelizes before the inside is done, too cool and it takes 5-6 hours. The goal is to soften the potato completely while drawing out all moisture.
The Cheese and Bacon Sauce
While the terrine cooks, Fallow makes the cheese sauce—which is technically a hot custard. Two whole eggs and six yolks are whisked with water, cream, and paprika, then cooked gently over a bain-marie to 75°C, whisking constantly to avoid scrambling. As it thickens, he folds in finely grated red Leicester (or red cheddar if American) and American cheese, which melts into the warm custard without breaking. The heat is turned off before adding the cheese so it stays emulsified. A touch of Dijon mustard at the end adds acidity. Separately, bacon lardons are fried until crispy. The result is a shiny, stable sauce that Fallow notes is versatile enough for other dishes. This cheese custard is far sturdier than a traditional cheese sauce thickened with roux.
Pressing, Portioning, and the Final Fry
After 3 hours, a knife should slide through the terrine with zero resistance. The mold is then weighted down (Fallow uses restaurant-grade weights, but at home a bottle of oil or milk works) and chilled in the fridge for 5-6 hours until completely set. Once chilled, the terrine is portioned into chunky chip-sized pieces—uniform in size so they fry evenly. Fallow notes these chips cannot be frozen; the remaining moisture causes the structure to collapse when thawed. They're fried at 180°C for about 5 minutes until golden and crispy. As soon as they hit the plate, they're salted lightly (remembering salt is already in the terrine itself) and topped with the crispy bacon bits and cheese custard. The final result is a chunky, crispy exterior that shatters into a creamy, perfectly cooked interior.