01 - Place chopped apples, brown sugar, apple cider, cinnamon, nutmeg, cloves, allspice, vanilla extract, and salt into a large heavy-bottomed saucepan. Stir to mix evenly.
02 - Heat over medium flame, stirring occasionally, until apples become very soft, approximately 30 minutes.
03 - Use an immersion blender to purée the softened apples until smooth. Alternatively, blend in batches with a countertop blender and return to the pot.
04 - Lower heat to low and simmer uncovered, stirring frequently for about 45 minutes until the mixture thickens and darkens to a spreadable consistency. Stir often to prevent sticking.
05 - Taste the apple butter and adjust sweetness or spices as desired. Allow to cool slightly.
06 - Toast bread slices until desired crispness is achieved. Optionally, spread each slice lightly with unsalted butter.
07 - Generously spread warm spiced apple butter over the toasted bread and serve immediately.