The culinary failure point for most cooks occurs at the stove burner. A roux made of equal parts all-purpose flour and unsalted butter provides the physical matrix that thickens the liquid base. Flour's amylose and amylopectin molecules absorb water and swell at roughly 180°F (82°C), forming a viscous gel.
Younger cooks her blonde roux for two to three minutes to remove raw wheat flavors without developing dark nutty notes that would clash with the dairy. Once the dairy is whisked in and thickened, the critical step begins: the heat must be turned off completely before any cheese is introduced.
Dumping shredded cheese into a simmering white sauce guarantees a broken emulsion. The residual heat stored in a heavy-bottomed Dutch oven or enameled cast iron pan is more than enough to melt cheese shreds smoothly. Incorporating the cheese in three or four gradual additions allows each handful to disperse into the warm fat-protein matrix without dropping the pot's temperature abruptly or shocking the proteins into contraction.
