You can use any bread but I've found that the Cinnabon bread works best.
Swapping standard sandwich bread for enriched loaves like Cinnabon bread alters the structural integrity of the dish completely. Enriched breads contain higher amounts of fat and sugar, which inhibits the rapid absorption of liquids. Standard sliced white bread dissolves into mush during an overnight soak, but denser, laminated, or frosted breads maintain their architecture.
Dry bread acts like a sponge through capillary action. When milk and eggs combine with sugar and cinnamon, proteins in the egg whites suspend the emulsion. Pouring half the liquid over the slices initially and flipping them guarantees the crumb absorbs the mixture evenly. Drain excess liquid before refrigeration to prevent sogginess. Resting the soaked bread uncovered or foiled in the refrigerator for eight to twelve hours allows starch molecules to fully hydrate and bind the dairy proteins.
Cooking requires careful thermal management. Set the griddle to medium-high heat, approximately 375 degrees Fahrenheit. Butter contains milk solids that brown rapidly; watch for the foam to subside as an indicator that water has evaporated from the fat. Cook each slice for three to four minutes per side until the exterior develops a deep mahogany crust and the internal temperature reaches 160 degrees Fahrenheit.