Step 1

Place the butter in a small pot and melt over low heat.

Step 2

Add the flour, brown sugar, cinnamon, and salt, and toss to combine.

Step 3

Preheat the oven to 350 degrees F, and mist a 9-inch springform pan with non-stick spray.

Step 4

Place the flour, sugar, baking powder, baking soda, and salt in the bowl of an electric mixer, and stir to combine.

Step 5

Add the butter, and mix on medium-low speed until the mixture resembles damp sand (about 2 minutes).

Step 6

Add the eggs, one at a time, mixing on low speed until smooth.

Step 7

Scrape the bottom and sides of the bowl with a silicone spatula, then add the sour cream, vanilla, and lemon juice.

Step 8

Beat on medium speed for about 1 1/2 minutes, to aerate the cake batter and build its structure.

Step 9

Transfer half the cake batter to the prepared pan.

Step 10

Top with half the topping, then spread the remaining batter on top (layers of cake batter may seem thin, but they will puff up as they bake).

Step 11

Sprinkle the remaining cinnamon crumb mixture on top, then bake the cake for 30 to 40 minutes, or until a toothpick inserted in the thickest part of the cake comes out clean or with a few moist crumbs.

Step 12

Cool completely, then dust with powdered sugar for garnish.