Step 1

Preheat oven to 350°F. Prepare the Batter: Coat a 13- x 9-inch baking pan with baking spray. Line bottom and sides of pan with parchment paper, leaving a 2- to 3-inch overhang on sides.

Step 2

Beat butter, brown sugar, and granulated sugar with a stand mixer fitted with a paddle attachment on medium speed until lightened and creamy, about 3 minutes. Add eggs 1 at a time, beating until just incorporated. Beat in vanilla until combined, stopping to scrape down sides as needed. Beat in sour cream until combined, stopping to scrape down sides as needed. Whisk together flour, cinnamon, baking soda, baking powder, and salt in a separate bowl; add to butter mixture, beating on low speed until combined. Fold in apples. Spoon mixture into prepared pan, spreading to edges.

Step 3

Prepare the Topping: Stir together brown sugar, flour, pecans, butter, and cinnamon in a medium bowl until mixture comes together. Sprinkle Topping evenly over Batter. Transfer to preheated oven; bake until Topping is golden and a wooden pick inserted center of cake comes out with moist crumbs, about 45 minutes. Let cool completely in pan on a wire rack, about 1 hour. Remove cake from pan using parchment paper as handles; transfer to wire rack.

Step 4

Prepare the Glaze: Whisk together powdered sugar, milk, and vanilla in a medium bowl until smooth. Drizzle over cake, and serve.