Preheat the oven to 375ºF. Lightly grease a 10-inch springform pan. Sprinkle with sliced almonds. Shake out any that do not stick to the pan and reserve for garnish.
For the Crumb Topping: Blend together the flour, almonds, brown sugar, butter, cinnamon and salt in the bowl of a mixer fitted with the paddle until dry and crumbling.
For the Cake Batter: Blend together the American Almond® almond paste and sugar in the bowl of a mixer fitted with the paddle until smooth, about 2 minutes. Add the butter, lemon juice, and vanilla extract. When smooth, add the eggs, one at a time, scraping down the bowl between each addition. Add the flour and blend well. Fold in the sliced apples.
Scrape the batter into the prepared pan. Smooth the top with a spatula. Scatter the crumb topping evenly over the batter. Sprinkle the reserved sliced almonds on top.
Bake the cake in the oven for 30 minutes. Reduce the heat to 325°F and bake until evenly browned, for approximately 20 to 30 additional minutes. Let cool 5 minutes in the pan then unmold onto a cooling rack.
To make the salted caramel sauce: Have all the ingredients for the caramel sauce measured out before you begin. Combine the sugar, water, and corn syrup in a small saucepan over medium heat. Stir until the sugar dissolves. Brush any sugar crystals that stick to the sides of the pan with a pastry brush dipped in clean water. Raise the heat to high and cook the sugar until it turns a deep amber color.
Immediately remove the pan from the heat. Pour in the cream, butter, and salt and carefully whisk the mixture until it is smooth.
Serve wedges of the cake with a spoonful of sour cream and a drizzle of the caramel sauce.
Variation: Try substituting white chocolate for the caramel drizzle.
