Brown Butter Apple Crumb Cake

Ingredients

• For the crumb topping: 3/4 cup all-purpose flour
• 1/2 cup old-fashioned rolled oats
• 1/2 cup packed light brown sugar
• 1 teaspoon ground cinnamon
• 1/4 teaspoon fine sea salt
• 6 tablespoons unsalted butter, melted and slightly cooled
• For the apples: 2 medium baking apples, peeled, cored, and diced into 1/2-inch pieces
• 1 tablespoon granulated sugar
• 1 tablespoon fresh lemon juice
• 1/2 teaspoon ground cinnamon
• For the cake: 10 tablespoons unsalted butter
• 1 3/4 cups all-purpose flour
• 1 teaspoon baking powder
• 1/2 teaspoon baking soda
• 3/4 teaspoon fine sea salt
• 3/4 cup granulated sugar
• 1/4 cup packed light brown sugar
• 2 large eggs, room temperature
• 2 teaspoons pure vanilla extract
• 3/4 cup full-fat sour cream, room temperature
• For the glaze: 3/4 cup powdered sugar
• 1 to 2 tablespoons whole milk
• 1/2 teaspoon pure vanilla extract
• Pinch of fine sea salt

Instructions

1. Place a rack in the center of the oven and heat to 350°F. Grease a 9-inch square baking pan and line it with parchment, leaving an overhang on two sides so the cooled cake can lift out cleanly.
2. Make the crumb topping first. In a medium bowl, stir together the flour, oats, brown sugar, cinnamon, and salt. Pour in the melted butter and mix with a fork until the mixture forms damp clumps. Refrigerate while you prepare the cake so the crumb holds its shape in the oven.
3. Toss the diced apples with the granulated sugar, lemon juice, and cinnamon. Set aside. The apples will release a little juice, which is fine; that moisture helps them soften into the cake.
4. Brown the butter for the cake. Add the 10 tablespoons butter to a light-colored saucepan and melt over medium heat. Continue cooking, stirring often, until the butter foams, the milk solids turn amber, and it smells nutty. Immediately scrape the butter and browned bits into a large heatproof mixing bowl. Let cool for 10 minutes.
5. In a separate bowl, whisk together the flour, baking powder, baking soda, and salt. This dry mix should be evenly combined before it touches the wet ingredients so the cake rises evenly.
6. Whisk the granulated sugar and brown sugar into the cooled brown butter. Add the eggs one at a time, whisking well after each addition. Whisk in the vanilla until the mixture looks glossy and slightly thick.
7. Add half of the dry ingredients to the butter mixture and fold gently with a spatula. Fold in the sour cream, then add the remaining dry ingredients. Stop mixing as soon as the last streaks of flour disappear; overmixing can make the crumb tough.
8. Spread about two-thirds of the batter into the prepared pan. Scatter the cinnamon apples evenly over the batter, leaving behind any excess liquid in the bowl. Dollop the remaining batter over the apples and gently spread it into a thin, uneven layer. It does not need to cover every apple piece.
9. Break the chilled crumb topping into large and small pieces with your fingers and scatter it over the surface. Bake for 45 to 55 minutes, or until the crumb is deeply golden and a tester inserted into the center comes out with a few moist crumbs but no raw batter.
10. Cool the cake in the pan for 25 minutes, then use the parchment to lift it onto a rack. Cool until just warm or room temperature before glazing.
11. Whisk the powdered sugar, 1 tablespoon milk, vanilla, and salt until smooth. Add more milk a few drops at a time until the glaze is thick but pourable. Drizzle over the cooled cake, slice into squares, and serve.

Tips

• Use a firm baking apple such as Honeycrisp, Pink Lady, Braeburn, or Granny Smith so the fruit softens without collapsing into applesauce.
• Do not walk away while browning butter. It can go from golden to burnt quickly once the foam begins to subside.
• Room temperature sour cream and eggs help the batter emulsify, giving the cake a finer, softer crumb.
• For clean slices, let the glaze set for 10 to 15 minutes and use a sharp knife wiped clean between cuts.

Storage

Store the cake covered at room temperature for up to 2 days, or refrigerate for up to 5 days. Bring chilled slices to room temperature before serving, or warm them briefly in a low oven. The unglazed cake can be frozen for up to 2 months; wrap individual slices tightly and thaw overnight in the refrigerator.

Variations

• Pear walnut crumb cake: replace the apples with firm diced pears and add 1/3 cup chopped toasted walnuts to the crumb topping.
• Maple glaze: replace the milk in the glaze with maple syrup for a deeper fall flavor.
• Cardamom apple cake: add 1/4 teaspoon ground cardamom to the cake batter and a pinch to the apples.
• Round coffee cake: bake in a 9-inch springform pan, checking for doneness around 50 minutes.

Nutrition note

Nutrition will vary depending on apple size, glaze thickness, and slice size. This is a dessert-style coffee cake with butter, sour cream, and sugar, so it is best enjoyed as an occasional homemade treat.

FAQ