For the apple pear butter: Place the apples and pears in the insert of a slow cooker. Pour the apple cider and maple syrup over the fruit, then drop the tea bag in and sprinkle with the salt. Gently stir to coat the fruit, being mindful not to break the tea bag. Cover and set to cook on high until the fruit is completely tender, about 8 hours. Discard the tea bag.
Scoop the fruit into the bowl of a food processor with a slotted spoon and pulse until smooth, working in batches if necessary, about 1 minute. Pour the fruit puree into a large nonstick pot. Place the pot over low heat and bring to a simmer, then simmer until the volume is reduced by a third and the color darkens and intensifies, 35 to 40 minutes.
For the pie crust dippers: Meanwhile, preheat the oven to 400 degrees F and line a baking sheet with parchment.
Place the round of pie dough on a cutting board. Add a splash of water to the beaten egg and brush the crust with the egg wash. Combine the sugar, apple pie spice and salt in a small bowl and sprinkle evenly over the pie dough. Use a pizza cutter or knife to slice the round into 20 strips. Place on the lined baking sheet and bake until golden brown and crispy, 10 to 15 minutes. Set aside to cool for a few minutes.
Serve the butter alongside the pie crust dippers or store in an airtight container, refrigerated, for up to 2 weeks. If preparing in advance, allow to cool completely before covering and storing.