Ingredients

• 1/2 cup unsalted butter
• 2 teaspoons unsalted butter
• 1 cup packed light brown sugar (can use dark brown sugar, the cake will just be darker)
• 2 large eggs
• 2 cups all-purpose flour
• 1 teaspoon baking soda
• 1 teaspoon ground cinnamon
• 1/2 teaspoon salt
• 1 cup light sour cream or 1 cup sour cream
• 1 teaspoon pure vanilla extract
• 3 cups peeled cored and chopped apples (use Granny Smith or another tart apple)
• 1/2 cup packed light brown sugar
• 1/2 cup all-purpose flour
• 1/2 teaspoon ground cinnamon
• 4 tablespoons unsalted butter, softened

Instructions

1. Preheat the oven to 350 degrees F. Lightly grease a 13 by 9-inch glass baking dish with 2 teaspoons of the butter.

2. In a large bowl, cream together the remaining stick of butter and sugar until light and fluffy. Add the eggs 1 at a time, beating after the addition of each. In a separate bowl or on a piece of parchment, sift together the flour, baking soda, cinnamon, and salt. Add to the wet ingredients, alternating with the sour cream and vanilla. Fold in the apples. Pour into the prepared baking dish, spreading out to the edges.

3. To make the topping, in a bowl, combine the sugar, flour, cinnamon, and butter, and mix until it resembles coarse crumbs. Sprinkle the topping over the cake and bake until golden brown and set, 35 to 40 minutes. Remove from the oven and let cool on a wire rack for at least 10 minutes.