This incredible crumb cake is deliciously moist and buttery and covered in a thick blanket of crispy crumb topping. Every bite of this cake is a match made in heaven with its rich cake layer and signature sweet-cinnamony streusel.
Preheat oven to 325F. Grease and line an 8x8" square baking pan with parchment paper. Set aside.
In a large mixing bowl, toss together all the dry ingredients for the crumb topping.
1 1/2 cups (190g) all-purpose flour, 1/3 cup (65g) granulated sugar, 1/3 cup (65g) lightly packed brown sugar, 1 tsp ground cinnamon, 1/4 tsp salt
Stir in the melted butter just until all is moistened and chunky.
1/2 cup (114g) unsalted butter, melted
In a large mixing bowl, cream together the butter and sugar. Mix in the eggs, one at a time, then mix in the sour cream and vanilla extract. The mixture might look curdled, but not to worry, it will come together when you add in the dry ingredients.
1/2 cup (114g) unsalted butter, softened, 1/2 cup (100g) granulated sugar, 2 large eggs, 1/3 cup sour cream, 2 tsp vanilla extract
Slowly stir in the flour, baking soda, and salt until just combined. The batter will be thick.
1 1/4 cup (155g) all-purpose flour, 1/2 tsp baking soda, 1/4 tsp salt
Spoon the cake batter into the prepared baking pan. Evenly crumble the streusel on top.
Bake for 40-50 minutes or until a toothpick inserted into the center comes out clean. Let cool and dust with powdered sugar before serving.
Notes
Leftovers can be stored at room temperature, tightly covered in saran wrap or placed in an airtight container for 3-4 days.To freeze: Tightly double wrap in aluminum foil or saran wrap, label and date, and store in the freezer for up to 2 months. Thaw overnight in the fridge. Bring to room temperature and dust with powdered sugar before serving.
Substitutions:
unsalted butter - salted butter (just omit the salt)
brown sugar - granulated sugar
all-purpose flour - cake flour or self-rising flour (omit the baking soda)