Averie Cooks

0 Add the potatoes to a large stockpot, cover with water, and then drain to remove some of the starch. Do not skip this step. This helps create a fluffier mashed potato texture because you're removing some starch. 
1 Add fresh water to the pot, about two inches above the potatoes, cover the     pot with a lid, and bring to a boil. Tip - I like to add 1 teaspoon kosher salt to the water for better flavor later on, but it's optional. Once the water begins to boil, remove the lid and boil the potatoes for 15-20 minutes over medium-high heat, or until the potatoes are fork tender and done. 
4 While the potatoes are boiling, in a separate small saucepan, add the butter, half-and-half, salt, pepper, and heat over medium heat to melt the butter. Set aside until the potatoes are done. Tips - Make sure just to get the butter melted, don't boil it or allow the heat to get too high. You don't want to boil the dairy proteins in the half-and-half. I recommend using half-and-half. Not whole milk, nor heavy cream. Half-and-half is perfect here. If you don't have half-and-half, you can make it by combining 3/4 cup whole milk with 3/4 cup heavy cream, and now you have 1 1/2 cups half-and-half. 
3 When the potatoes are cooked, drain the remaining cooking liquid. I find it easiest to just flip the potatoes into a colander over the sink and allow the cooking water to run out.
2 If they're not already in one, place the potatoes into a colander and briefly rinse them under cold water after draining. Shake the excess moisture off. Do not skip this step. This helps create a fluffier mashed potato texture because you're removing some starch. 
5 Transfer the potatoes to a large mixing bowl and pour the melted butter mixture over the potatoes. 
6 Using a potato masher (or potato ricer, or even just a large fork), mash the potatoes. Do NOT use an electric appliance like a mixer, blender, food processor, etc. Do this by hand for the best texture otherwise the potatoes could turn gummy or gluey. 
7 Transfer the potatoes into a 9x13-inch baking dish or similar sized casserole dish and allow the potatoes to cool completely. Cover tightly with foil and refrigerate the potatoes for up to 3 days. 
8 Reheating -  When ready to reheat the mashed potatoes, remove the dish from the refrigerator and let sit at room temperature for 15-30 minutes while the oven preheats to 350F.
9 Add ½ cup of half-and-half and 2 tablespoons of butter to a small saucepan, heat over medium heat to melt the butter, and lightly warm the half-and-half. 
10 Pour this mixture on top of the mashed potatoes, do NOT stir it in. Just let it sit on top. 
11 Cover the casserole dish tightly with the foil and bake for 20-25 minutes, or until the mashed potatoes have heated through. Stir, fluff, and serve warm.