To balance all the intensity up top, I leave the cake batter below relatively plain — a buttery yellow cake scented with vanilla.
The cake keeps for a week and it only gets better and better the further I get from the day I had to put in the work to bake it.
Brown Butter-cinnamon Crumb Cake
Time 2 hours, largely unattended.
A springform pan is best because you can remove the sides and slide the cake out without disturbing the crumbs on top. If you have only a plain cake pan, though, that will work too; just make sure it’s at least 3 inches tall on the sides so the crumbs and batter don’t spill while baking.
3/4 cup (11/2 sticks) unsalted butter, plus more for greasing
2 tablespoons high-quality ground cinnamon (see note)
2 cups all-purpose flour
3/4 cup granulated sugar
1/4 cup packed light brown sugar
1 1/2 teaspoons kosher salt, preferably Diamond Crystal
1/2 cup (1 stick) unsalted butter, at room temperature, plus more for the pan
2 cups all-purpose flour, plus more for rolling
2 teaspoons baking powder
1 teaspoon kosher salt, preferably Diamond Crystal
1/4 teaspoon baking soda
1 cup granulated sugar
1 tablespoon pure vanilla extract
2 large eggs
1/3 cup sour cream
1 cup whole milk
Powdered sugar, to garnish (optional)
Make the crumb topping: Put the butter in a medium skillet and place over medium-high heat. Once the butter melts, continue cooking, whisking occasionally, until the butter foams and then starts to smell nutty, 3 to 5 minutes. As soon as you see light brown flecks on the bottom of the skillet (these are the milk solids caramelizing), remove the pan from the heat and use a heatproof rubber spatula to scrape the butter and all the browned bits on the bottom of the pan into a medium bowl. Whisk in the cinnamon until smooth, then place the bowl in the freezer for 10 minutes, stirring two or three times while it chills, to cool the butter until no longer warm.