Preheat oven to 350°F. Coat your baking dish with nonstick cooking spray. Set aside.
Streusel: Combine melted butter, brown sugar, cinnamon, salt, flour, and pecan pieces in a medium bowl. Stir until combined.
Cake: Using a stand mixer bowl fitted with the paddle attachment, beat the butter and the sugar together on medium for approximately 2 minutes. Add in the eggs and continue mixing on medium for 2 more minutes, scraping down the sides of bowl as necessary.
Add in the vanilla, sour cream, salt, baking powder, and baking soda. Mix until combined. Turn the mixer to low and add the flour until well combined.
Spread half of the batter in the bottom of the prepared pan. Sprinkle half of the streusel mixture on top of the batter. Carefully spread the remaining batter on top of the streusel, spreading it out with a spatula. Sprinkle the remaining streusel ingredients on top.
Bake for 45 - 50 minutes in preheated oven. Use a toothpick to insert into the center of the cake to check doneness.
Cool on wire rack for minimum 10 minutes before serving.
Just before serving, dust with powdered sugar.