Apple and Olive Oil Cake with Maple Icing

Name: Apple and Olive Oil Cake with Maple Icing
Ingredients: heaping 1/2 cup / 80 g raisins; 4 tbsp water; 2 1/4 cups / 280 g all-purpose flour; 1/2 tsp ground cinnamon; 1/4 tsp salt; 1/2 tsp baking powder; 1 1/4 tsp baking soda; 1/2 cup / 120 ml olive oil; 3/4 cup / 160 g superfine sugar; 1/2 vanilla bean; 2 free-range eggs, lightly beaten; 3 large Granny Smith apples, peeled, cored, and cut into 3/8-inch / 1-cm dice; grated zest of 1 lemon; 2 free-range egg whites; confectioners' sugar for dusting (optional); 7 tbsp / 100 g unsalted butter, at room temperature; scant 1/2 cup / 100 g light muscovado sugar; scant 6 tbsp / 85 ml maple syrup; 8 oz / 220 g cream cheese, at room temperature