Preheat the slow cooker if necessary; see the manufacturer's instructions. Heat the butter, sugar and syrup in a saucepan or in a bowl in the microwave until the butter has just melted.
Add the apples and lemon juice to the slow cooker pot and toss together. Stir the butter mix and pour it over the apples. Cover with the lid and cook on high for 1–1½ hours or until the apples are tender but still holding their shape.
Heat the pancakes in a frying pan or the microwave, according to the pack instructions. Fold in half and arrange on serving plates. Stir the apple mix, then spoon it on to the pancakes. Top with a scoop of vanilla ice cream.