Equipment Needed
- 9×13 inch baking pan
- Parchment paper (optional but a lifesaver for cleanup)
- Mixing bowls (one large, one medium)
- Whisk and rubber spatula
- Measuring cups and spoons
- Small bowl for the cinnamon sugar
- Fork or small whisk for the glaze
- Toothpick or cake tester
Step-by-Step Instructions
First, I preheat my oven to 350°F (175°C) and generously grease my 9×13 pan. For absolute foolproof removal, I’ll sometimes line it with a sling of parchment paper, leaving an overhang on the two long sides. It feels like an extra step, but it’s worth it for perfect slices. In my largest bowl, I combine the yellow cake mix, eggs, vegetable oil, and sour cream. Now, I use my trusty whisk and really beat it by hand for a good two minutes until the batter is completely smooth, thick, and beautifully glossy. This ensures everything is perfectly emulsified and promises an even rise. I set this aside while I prepare the magical swirl.
In a medium bowl, I mix the granulated sugar, brown sugar, and cinnamon until they’re fully united. The smell alone is heavenly. I gently toss my diced strawberries in about two tablespoons of this cinnamon sugar mixture—this little trick helps prevent them from all sinking to the bottom during baking. Then, I pour about half of the thick cake batter into my prepared pan, spreading it into a somewhat even layer. It will be a relatively thin layer, and that’s perfectly fine. This is where we build the flavor.
Here comes the fun part: creating the swirl. I sprinkle almost all of the remaining cinnamon sugar mixture evenly over this first layer of batter. Then, I scatter the sugar-tossed strawberries over the top. Using a butter knife or a small offset spatula, I gently swirl everything together, dragging the knife in wide, loose “S” shapes through the batter and toppings. Don’t overdo it—just 4 or 5 passes is plenty. We want pockets of cinnamony strawberry goodness, not a homogenous mix. Then, I carefully pour and spread the remaining batter over the top, sealing in all that swirl.
The final touch before baking is a light sprinkle of the last bit of cinnamon sugar over the top batter. This creates that signature, slightly crackly, sugary crust. I pop the pan into the center of my preheated oven and set my timer for 45 minutes. I’ve learned the hard way that oven temperatures can vary, so I start checking at the 40-minute mark. The cake is done when the top is a deep golden brown, the edges are pulling away from the pan, and a toothpick inserted into the center comes out with just a few moist crumbs (not wet batter). While it bakes and fills my home with that incredible aroma, I whisk together the simple vanilla glaze.(See the next page below to continue…)