For the crumb topping:

1. Place the butter, flour, sugar, salt, and lemon zest in a small bowl and stir together with a fork until crumbly.

For the cake:

1. Preheat the oven to 350 degrees F and mist a 9-inch diameter springform pan with non-stick spray.
2. Place the flour, sugar, baking powder, baking soda, and salt in a large mixing bowl and whisk to combine.
3. Add the softened butter, and mix on medium-low speed until the mixture resembles damp sand.
4. Stir in the eggs, one at a time, stopping to scrape the bottom and sides of the bowl with a silicone spatula after each addition.
5. Add the sour cream, vanilla, lemon juice, and lemon zest, and mix on medium-high speed for 60 to 90 seconds, to aerate the batter and build the cake’s structure.
6. Transfer about half the batter to the prepared pan. Top with apples and raspberries.
7. Sprinkle with half of the crumb topping, then spread the remaining cake batter on top.
8. Top with the remaining crumb topping, and bake for 40 to 50 minutes, or until a toothpick inserted in the thickest part of the cake comes out clean or with a few moist crumbs.
9. Cool completely, and drizzle with raspberry glaze.

For the glaze:

1. Place the raspberries in a mini-chopper or food processor with 1/4 cup of the sugar, and pulse until pureed smoothly.
2. Transfer the puree to a small bowl, and stir in the remaining powdered sugar.