1-To start, preheat your oven to 350°F (175°C) and grease a 9×13-inch baking pan or line it with parchment paper for easy removal.

2-Begin by preparing the crumb topping: combine the brown sugar, granulated sugar, cinnamon, and salt in a bowl, then stir in the melted butter and mix in the flour until it forms crumbles. For the best results, chill the crumb topping in the fridge or freezer until you’re ready to use it.

3-Next, for the cake batter, whisk together the flour, baking soda, baking powder, and salt in a separate bowl.

4-Now, beat the softened butter and granulated sugar until creamy, then add the eggs one at a time, followed by the sour cream and vanilla extract.

5-Gradually mix in the dry ingredients with the wet mixture to avoid overworking the batter. Toss the chopped apples with cinnamon to enhance their flavor, then spread the batter evenly into your prepared pan.

6-Layer the cinnamon-coated apples over the batter and firmly press the chilled crumb topping on top for that signature crunch.

7-Bake the cake for 45 to 55 minutes, checking with a toothpick to ensure it’s done if the top browns too quickly, cover it with foil.

8-Once baked, let the cake cool for 30 to 45 minutes before slicing, and feel free to add an optional icing drizzle for extra sweetness.