Preheat the oven to 350 degrees Fahrenheit and place a rack in the upper third of the oven. Line a 13x9 pan with parchment paper, spray with nonstick spray, or grease with butter or coconut oil.

For Cinnamon Struesel Topping- In a medium bowl, whisk together the sugar, flour and cinnamon. Stir in the butter until evenly coated and set aside.

For Brown Sugar Filling- In a small bowl, whisk together the brown sugar, cinnamon, nutmeg, cocoa powder and salt. Set aside.

For Cake- Using an electric mixer with a paddle attachment, beat together the butter and sugars until very well combined, about 4 minutes.

Beat in the vanilla.

Add the eggs, one at a time, beating for 1 minute after adding each one. Scrape the sides of the bowl as needed.

In a small bowl, whisk together the flour, baking powder, and salt.

In another small bowl, whisk together the milk and sour cream (or yogurt) until well combined. No need to whisk out all the lumps.

With the mixer on low speed, add 1/3 of the flour mixture to the batter.

As it's mixing, add 1/2 of the milk mixture.

Add another 1/3 of the flour mixture.

Add the rest of the milk mixture.

Add the remaining 1/3 of the flour mixture and mix until well combined, scraping down the sides of your bowl.

Spread half of your batter in the bottom of your prepared pan, making sure to spread it to the edges.

Sprinkle your brown sugar filling on top of the batter.

Dollop the rest of your cake batter on top of your filling, using a spatula to spread the batter across the pan.

Using a butter knife, gently swirl the filling into the batter.

Sprinkle all of the topping on your cake.

Bake for 50-55 minutes, or until the cake is golden brown and a toothpick comes out clean. Allow to cool before serving. Cake will last at room temperature for about 5 days. Enjoy!