Step 1: Preheat the Oven
• Preheat your oven to 350°F (175°C). Grease and flour a 9×13-inch baking pan.

Step 2: Prepare the Cake Batter
• In a large bowl, combine the yellow cake mix, eggs, sour cream, vegetable oil, and vanilla extract. Mix until well combined and smooth.

Step 3: Prepare the Cinnamon Swirl
• In a small bowl, mix together the granulated sugar and ground cinnamon. Set aside.

Step 4: Layer the Cake
• Pour half of the cake batter into the prepared baking pan and spread evenly.
• Spoon the strawberry preserves over the batter. If using, sprinkle the chopped strawberries on top of the preserves.
• Pour the remaining cake batter over the strawberry layer and spread gently to cover.
• Sprinkle the cinnamon-sugar mixture evenly over the top of the cake. Use a knife to gently swirl the cinnamon mixture into the batter.

Step 5: Bake the Cake
• Bake in the preheated oven for 40-45 minutes, or until a toothpick inserted in the center comes out clean.
• Allow the cake to cool in the pan for about 10-15 minutes before transferring to a wire rack to cool completely.

Step 6: Prepare the Glaze
• In a medium bowl, whisk together the powdered sugar, milk, and vanilla extract until smooth. Adjust the consistency by adding more milk for a thinner glaze or more powdered sugar for a thicker glaze.

Step 7: Glaze the Cake
• Once the cake is completely cooled, drizzle the glaze over the top.