Mashed potatoes can be reheated effectively using three main methods: the stove, microwave, or oven, each with some tips to keep them moist and creamy. On the stove, place mashed potatoes in a medium saucepan or Dutch oven, add a tablespoon of butter and a splash of milk, then heat on low for 8-10 minutes, stirring frequently to prevent sticking and ensure even heating. In the microwave, cover the potatoes and heat at high power for 1 minute, stir, then continue reheating in 30-second increments, stirring in between. Using half power and adding warm milk and butter after reheating can keep them moist. In the oven, bring potatoes to room temperature, preheat to 350°F, add milk and butter, cover, and heat for 15-20 minutes until warmed through, then stir in the liquids for fluffiness. Adding butter and milk in all methods helps to restore moisture and richness. Additional methods include reheating in a slow cooker with a splash of cream or milk on medium-low heat, or using a water bath bain-marie method by placing sealed mashed potatoes in a pan of simmering water to warm gently. Avoid reheating directly from frozen; thaw first for better texture. These methods help prevent drying out and maintain creamy texture as if freshly made.