Ingredients:

  • 8 medium firm, tart apples (e.g., Granny Smith), peeled, cored, and sliced 1/4-inch thick
  • 1/4 cup granulated sugar
  • 3 Tbsp packed brown sugar (for filling)
  • 1 Tbsp all-purpose flour or cornstarch (for filling)
  • 1 Tbsp lemon juice
  • 1 tsp ground cinnamon (for filling)
  • 1/2 tsp ground nutmeg
  • 1/4 cup water or apple cider
  • 1 1/2 cups old-fashioned rolled oats
  • 1/2 cup all-purpose flour (for topping)
  • 1/2 cup packed dark brown sugar (for topping)
  • 1/2 tsp ground cinnamon (for topping)
  • 1/4 tsp kosher salt
  • 1 stick (1/2 cup) cold unsalted butter, cubed

Instructions:

  1. Prepare the Filling: In a large bowl, toss the sliced apples with the granulated sugar, 3 Tbsp brown sugar, 1 Tbsp flour/cornstarch, lemon juice, 1 tsp cinnamon, and nutmeg until every slice is coated.
  2. Load the Slow Cooker: Pour the 1/4 cup of water or cider into the bottom of the slow cooker insert. Add the prepared apple mixture, spreading it into an even layer.
  3. Mix Dry Topping: In a separate medium bowl, whisk together the oats, 1/2 cup flour, 1/2 cup brown sugar, 1/2 tsp cinnamon, and salt for the topping.
  4. Incorporate Butter: Use a pastry blender, two forks, or your fingertips to cut the cold, cubed butter into the dry oat mixture until large, coarse, pea-sized crumbs form.
  5. Assemble and Cook: Sprinkle the crumb topping evenly over the apples. Cover the slow cooker and cook on LOW for 3 to 4 hours, or on HIGH for 1.5 to 2 hours, until the apples are fork-tender and the filling is bubbly.
  6. Check Topping Consistency (Optional Crisp Finish): For a crispier topping, carefully transfer the crisp to a casserole dish and bake in a preheated oven at 350°F (175°C) for 10-15 minutes, or place the slow cooker insert under a broiler for 2-3 minutes, watching carefully.
  7. Rest: Allow the crisp to cool, uncovered, for 15-20 minutes before serving to allow the filling to set.