Step 1

Place apple slices in a slow cooker. Stir sugar and apple pie spice with the apples.

Step 2

Cook on High for 4 hours; stir. Remove cover and continue cooking until the apples are very tender and most of the liquid has evaporated, 2 to 2 1/2 hours.

Step 3

Scrape apple butter into a bowl; refrigerate 8 hours to overnight.

Step 4

Blend apple butter with an immersion blender until smooth. Alternately, you can run the butter through a food mill or blend in a blender.