Peach Cobbler Coffee Cake

Step 1
Preheat the oven to 350 degrees F (175 degrees C). Lightly grease and line a 9×13-inch baking pan with parchment paper. (Allow 1 inch or so of parchment to hang over the sides of the pan if you wish to remove your cake from the pan to slice and serve.)

Step 2
Prepare the topping: Whisk together flour, pecans, white and brown sugars, cinnamon, and salt in a medium bowl. Add butter pieces and use a fork to work them into the dry mixture, stirring and cutting until combined. Refrigerate topping mixture until needed.

Step 3
Prepare the peach filling: Combine peach slices, 1/2 cup brown sugar, cornstarch, and cinnamon in a medium saucepan; gently toss to combine and coat. Place the pan over medium heat; cook, stirring occasionally, until the sugar dissolves and mixture becomes thick and syrupy, 6 to 8 minutes. Remove from heat and set aside to cool.

Step 4
Prepare the cake: Beat together sugar, butter, vanilla, and salt in the bowl of a stand mixer fitted with a paddle attachment until combined and fluffy, 4 to 5 minutes. Mix in eggs, 1 at a time, beating well after each addition.

Step 5
Combine flour and baking powder in a separate bowl. Whisk together buttermilk and sour cream in another separate bowl.

Step 6
Add the flour mixture to the butter mixture in 3 additions, alternating with the sour cream mixture, beating at a low speed to combine.

Step 7
Pour about 2/3 of the batter into the prepared pan. Sprinkle the remaining 1/2 cup of brown sugar from the filling over the batter; use a silicone spatula to gently smooth into an even layer. Spoon the peach filling evenly over the brown sugar; again, use a silicone spatula to gently smooth into an even layer. Spread the remaining batter over the peach filling. Sprinkle the topping mixture evenly over the cake.

Step 8
Bake cake in the preheated oven until golden brown at the edges and cooked through, 70 to 80 minutes, rotating the pan halfway through baking. (Cover the pan with aluminum foil after the first hour of baking if the topping looks dark enough.) Transfer the pan to a wire rack to cool for at least 30 to 40 minutes before slicing.