Heat oven to 350 degrees F. Lightly grease a 9" x 9" baking pan or casserole dish.
Spread half of the diced potatoes in bottom of pan.
Place the diced chicken breasts evenly on top.
Season chicken with 1/4 teaspoon each salt and pepper.
Sprinkle with half the bacon crumbles, 1/2 cup of the cheese, and half the green onions.
Spread the remaining diced potatoes on top, followed by the remaining bacon, another 1/2 cup cheese, remaining green onions and another 1/4 teaspoon each salt and pepper.
Pour heavy cream over top of casserole and then dot with the butter.
Cover with aluminum foil and bake in the preheated oven for 1 hour.
Uncover and bake another 30 minutes.
In the last few minutes of baking, sprinkle with the remaining 1/2 cup cheddar cheese and bake until melted.
Serve.
Bubbling heavy cream emulsifies with rendered bacon fat and melting cheddar to coat starches released from the russet potatoes during baking. When building a layered casserole containing raw poultry and starchy tubers, moisture management dictates the outcome. Russets contain high levels of amylase and amylopectin, which break down under heat to thicken surrounding liquids into a sauce. However, raw diced chicken breasts release significant intracellular water as protein coagulates between 140 degrees F and 165 degrees F. Covering the baking dish with aluminum foil for the initial 60 minutes traps steam, ensuring the potatoes soften fully before the surface browns. Removing the cover for the subsequent 30 minutes allows excess moisture to evaporate, concentrating the dairy solids and rendering the bacon fat crisp rather than rubbery.
Managing Starch and Protein Interactions
Layering requires precise seasoning because salt draws moisture from the chicken and potatoes via osmosis, distributing flavor evenly through the heavy cream. Dotting the top with unsalted butter introduces milk solids that undergo the Maillard reaction during the uncovered phase, yielding a golden crust. Staggering the cheddar cheese additions prevents the proteins from tightening into a tough, oily mass during the prolonged baking cycle.
Cut potato cubes to uniform sizes around one-half inch to ensure even starch gelatinization.
Check internal chicken temperature with a digital probe inserted into the largest piece, confirming it reaches 165 degrees F before serving.
Add the final half-cup of cheddar strictly in the last three minutes to retain cheese elasticity.