6–8 large Granny Smith or Honeycrisp apples, peeled, cored, and sliced
1 tablespoon lemon juice
1 teaspoon vanilla extract
1 cup old-fashioned rolled oats
1 cup light brown sugar, packed
1/2 cup all-purpose flour
1 tablespoon ground cinnamon
1/4 teaspoon ground nutmeg
1/2 cup unsalted butter, cold and cubed
Instructions
In a large bowl, toss the sliced apples with the lemon juice and vanilla extract. This helps prevent the apples from browning too quickly and adds a bright layer of flavor. Place the coated apples into the bottom of a greased 4 to 6-quart slow cooker, spreading them out evenly.
In a separate medium bowl, combine the rolled oats, brown sugar, flour, cinnamon, and nutmeg. Use a pastry cutter or your fingers to work the cold, cubed butter into the mixture. Continue until the mixture looks like coarse crumbs and the butter is evenly distributed.
Sprinkle the oat topping evenly over the apples in the slow cooker. To prevent the topping from becoming soggy, place a double layer of paper towels across the top of the slow cooker before putting the lid on. This catches the condensation that usually drips back onto the food.
Cover the slow cooker with the lid and cook on High for 2.5 to 3 hours, or on Low for 5 to 6 hours. The apple crisp is finished when the apples are tender when pierced with a fork and the topping has set. For a crispier top, you can vent the lid slightly during the last 30 minutes of cooking.