1-First Step: Crisp the Bacon Start by cooking your bacon properly. Place chopped streaky bacon in a cold non-stick pan over medium heat. The key here is starting cold this allows the fat to render slowly, resulting in evenly crispy bacon without burning. No additional oil is needed since streaky bacon has enough fat content to cook in its own rendered fat. Cook until golden and crispy, about 8-10 minutes, stirring occasionally. Transfer the cooked bacon to paper towels to drain excess grease and cool completely before handling.

2-Second Step: Prepare the Potatoes While the bacon cooks, peel your potatoes and cut them into even 3 cm (about 1-inch) chunks. Keeping pieces uniform ensures they cook at the same rate. Place the cut potatoes in a large pot and cover with cold water, about 10 cm above the potatoes. Starting with cold water is crucial adding potatoes to already boiling water causes the outside to overcook before the inside becomes tender. Add a tablespoon of cooking salt to the water. This seasons the potatoes throughout rather than just on the surface. Bring to a boil over high heat, then reduce to a rapid simmer for approximately 15 minutes or until the potatoes are very soft. Test doneness by inserting a knife or fork it should slide in with zero resistance.

3-Third Step: Drain and Steam Once tender, drain the potatoes thoroughly in a colander. Return them to the still-warm pot and let them steam for 1 minute while gently shaking the pot occasionally. This step might seem small, but it’s essential for fluffy mash. Steaming evaporates surface moisture that would otherwise make your mashed potatoes gummy and watery.

4-Fourth Step: Mash and Season Now for the satisfying part. Add the milk (including the extra 2/3 cup if making ahead), cubed butter, sour cream, and teaspoon of salt to the pot. Using a disc-style potato masher, work through the potatoes until smooth. Mash in a gentle pressing motion rather than vigorous stirring overworking releases excess starch that turns potatoes sticky. Important: Resist the urge to use a food processor or blender. These appliances overwork the starches and create a gluey, paste-like texture that no amount of butter can fix. A hand masher or potato ricer gives you control and maintains that perfect, fluffy consistency.

5-Fifth Step: Prepare for Baking If making ahead, allow the mash to cool completely, cover tightly, and refrigerate for up to 3 days. When ready to bake, preheat your oven to 200°C (400°F), or 180°C for fan-forced ovens. Transfer the mashed potatoes to a 2-liter (2 quart) baking dish. Spread evenly and smooth the surface with a spatula. An even surface helps the cheese melt uniformly across the top.

6-Sixth Step: Add the Toppings Sprinkle the shredded mozzarella and cheddar (or Red Leicester) evenly across the surface. Follow with the cooled, crispy bacon pieces, distributing them so every bite gets some of that smoky goodness. The cheese and bacon layer serves a dual purpose: it adds incredible flavor while sealing in moisture during baking.

7-Final Step: Bake and Serve Cover the dish loosely with aluminum foil this prevents the cheese from over-browning before the center heats through. Bake for 20 minutes if freshly made, or 35 minutes if reheating a refrigerated casserole. Then remove the foil and bake for another 10 minutes until the cheese is bubbling and golden in spots. Remove from the oven and sprinkle with the finely sliced green onion. Let it rest for 5 minutes before serving. This brief rest makes serving easier and allows the flavors to settle. If you’re looking for more inspiration, check out these creative mashed potato variations from other home cooks.