Circle B Kitchen
If you'd like to halve the recipe, it bakes up nicely in a 9-inch cake pan. I place a piece of parchment paper in the bottom of the cake pan and then spray it with nonstick cooking spray. It comes out very easily and looks nice for serving. You can also forego the 9x13 pan altogether and make this in two 9-inch cake pans and freeze one for later.
Recipe from Epicurious
Topping:
1 cup (packed) dark brown sugar
1/2 cup sugar
1 1/2 tablespoons ground cinnamon
1/2 teaspoon salt
1 cup (2 sticks) unsalted butter, melted, warm
2 1/2 cups all purpose flour
Cake:
2 1/2 cups all purpose flour
1 teaspoon baking soda
3/4 teaspoon baking powder
1/2 teaspoon salt
3/4 cup (1 1/2 sticks) unsalted butter, room temperature
1 1/2 cups sugar
2 large eggs
1 1/3 cups sour cream (or yogurt - I used half sour cream, half yogurt)
1 teaspoon vanilla extract
For topping:
Mix both sugars, cinnamon, and salt in medium bowl and whisk to blend. Add warm melted butter and stir to blend. Add flour and toss with fork until moist clumps form (topping mixture will look slightly wet). Set aside.
For cake:
Position rack in center of oven and preheat to 350°F. Butter a 13 x 9 x 2-inch glass baking dish or a 9-inch cake pan. Sift flour, baking soda, baking powder, and salt into medium bowl. (I didn't sift, just used a whisk to combine the dry ingredients once they were in the bowl).
Using electric mixer, beat room-temperature butter in large bowl until smooth. Add sugar and beat until light and fluffy. Add eggs 1 at a time, beating until well blended after each addition. Add sour cream and vanilla extract and beat just until blended. Add flour mixture in 3 additions, beating just until incorporated after each addition.
Transfer cake batter to prepared baking dish; spread batter evenly with rubber spatula or offset spatula. Squeeze small handfuls of topping together to form small clumps. Drop topping clumps evenly over cake batter, covering completely (topping will be thick).
Bake cake until tester inserted into center comes out clean and topping is deep golden brown and slightly crisp, about 1 hour if using a 9x13-inch pan. If using 9-inch cake pans, begin checking at 35 minutes. Cool cake in dish on rack at least 30 minutes.
DO AHEAD: Can be made 1 day ahead. Cool completely. Cover and let stand at room temperature.
Cut cake into squares and serve slightly warm or at room temperature.