Place the chopped peaches and lemon juice into a large, heavy-bottomed pot or Dutch oven.

Cook the peaches over medium heat, stirring occasionally, until they have completely broken down and released a significant amount of liquid (about 30 to 45 minutes).

Stir in the granulated sugar and all the ground spices (cinnamon, nutmeg, allspice). Bring the mixture to a gentle simmer.

Reduce the heat to low, allowing the mixture to cook very slowly. Continue to cook, uncovered, for another 2 to 3 hours, stirring every 15-20 minutes to prevent scorching on the bottom. The butter is done when it is very thick, dark in color, and significantly reduced in volume.

For the smoothest texture, carefully transfer the hot peach butter to a blender or use an immersion blender to process until completely smooth. Return the pureed mixture to the pot.

Simmer for a final 10 minutes to ensure proper consistency. Ladle the hot peach butter into sterilized jars, leaving 1/4 inch headspace, and seal according to safe canning procedures, or refrigerate immediately.