For the cake batter –
4 tablespoons + 1 tablespoon unsalted butter, room temperature – divided
3/4 cup + 1 tablespoon packed brown sugar, divided
1 large egg, room temperature
1 teaspoon vanilla extract
1 cup (120 grams) all purpose flour
1/2 teaspoon baking soda
3/4 + 1/8 teaspoon ground cinnamon, divided
1/4 teaspoon salt
1/2 cup sour cream
1 cup peeled, cored, and chopped apples
1 tablespoon water
For the crumble –
1/4 cup (30 grams) all purpose flour
1/4 cup brown sugar
1/4 teaspoon cinnamon
2 tablespoons unsalted butter, room temperature
For the glaze –
1 cup powdered sugar
2 tablespoons heavy cream
- Preheat oven to 350 degrees. Begin by caramelizing the apples – melt 1 tablespoon butter in a small saute pan over medium heat. Add in the chopped apples, and cook over medium heat until they start to caramelize and become tender, 2-3 minutes (you can cover the saute pan with a lid with 60 seconds to trap in the steam to tenderize the apples more quickly).
- Mix in 1 tablespoon of brown sugar, 1 tablespoon water, and 1/8 teaspoon of ground cinnamon. Cook the apples until the brown sugar melts, about 60 seconds. Take the apples off the heat and let cool for at least 10 minutes before mixing into the cake batter.
- To make the cake batter – in a large bowl, mix together the remaining 4 tablespoons of butter and brown sugar until well combined and no streaks of butter remain. Add in the large egg, and whisk until light and creamy, about 45 seconds. Add in 1 teaspoon of vanilla extract and mix.
- In another bowl, whisk together the flour, 3/4 teaspoon cinnamon, baking soda, and salt. Add to the wet ingredients in 3 batches, alternating with the sour cream. Fold in the caramelized apples. Pour the batter into a 9 inch cake pan greased with cooking spray, oil, or butter.
- To make the crumble – place 1/4 cup flour, 1/4 cup brown sugar, 1/4 teaspoon cinnamon, and 2 tablespoons unsalted butter into a small bowl. Mix everything together thoroughly until the crumble looks like wet sand.
- Sprinkle the crumble evenly over the top. Bake the coffee cake until golden brown and set, 35-40 minutes. Let cool before topping with powdered sugar glaze.
- To make the glaze – whisk together the powdered sugar and heavy cream, until a thick glossy glaze forms. Add more heavy cream or more powdered sugar depending on how you like the consistency.
- Drizzle the glaze over the cooled cake. Let the cake sit overnight if you want the glaze to harden, or serve immediately.