Step 1: Wash peaches thoroughly. To peel, bring a large pot of water to a rolling boil. Carefully drop peaches into the boiling water for 30-60 seconds, then immediately transfer them to an ice bath. Once cool enough to handle, the skins should easily slip off.
Step 2: Halve the peeled peaches, remove the pits, and chop the flesh into 1-inch pieces. You should have approximately 4-5 pounds of prepared peach flesh.
Step 3: In a large, heavy-bottomed pot or Dutch oven, combine the chopped peaches, granulated sugar, lemon juice, ground cinnamon, ground nutmeg, and ground cloves. Stir well to combine.
Step 4: Bring the mixture to a boil over medium-high heat, stirring frequently. Once boiling, reduce the heat to low, cover, and simmer for about 20-30 minutes, or until the peaches are very soft. Stir occasionally to prevent sticking.
Step 5: Once the peaches are soft, remove the pot from the heat. For a smooth butter, use an immersion blender directly in the pot to purée the mixture until smooth. Alternatively, carefully transfer the hot peach mixture in batches to a regular blender or food processor and blend until smooth. Be cautious when blending hot liquids; leave the lid slightly ajar to allow steam to escape.
Step 6: Return the puréed peach mixture to the pot. Continue to simmer over low heat, uncovered, stirring very frequently (especially as it thickens) to prevent scorching. This slow cooking allows the water to evaporate and the flavors to concentrate. The butter is ready when it is thick enough to mound on a spoon and holds its shape, or when a spoonful placed on a chilled plate doesn’t separate. This can take anywhere from 1.5 to 3 hours.
Step 7: Once the peach butter has reached your desired consistency, carefully ladle it into hot, sterilized canning jars, leaving 1/4-inch headspace. Wipe the rims clean with a damp cloth.
Step 8: Apply new, hot lids and screw on bands until fingertip tight. Process the jars in a boiling water canner for 10 minutes (adjust for altitude).
Step 9: Remove jars and let them cool undisturbed on a towel for 12-24 hours. Check seals. Any unsealed jars should be refrigerated and consumed within 3 weeks. Properly sealed jars can be stored in a cool, dark place for up to 1 year. Alternatively, store in airtight containers in the refrigerator for 3-4 weeks or freeze for up to 6 months.