Preheat your oven to 350°F (175°C). Grease a 9×13 inch baking pan.

In a large mixing bowl, combine the vanilla cake mix, eggs, sour cream, vegetable oil, and vanilla extract. Mix until well blended and smooth.

In a small bowl, mix the brown sugar and ground cinnamon.

Pour half of the cake batter into the greased baking pan. Sprinkle half of the cinnamon-sugar mixture over the batter. Then, layer the diced strawberries evenly on top.

Pour the remaining cake batter over the strawberries and sprinkle the rest of the cinnamon-sugar mixture on top. Use a knife to gently swirl the mixture into the batter.

Bake in the preheated oven for 30-35 minutes or until a toothpick inserted into the center comes out clean.

While the cake is baking, prepare the creamy icing by mixing powdered sugar, milk, and strawberry puree in a bowl until smooth and creamy.

After baking, let the cake cool for about 10 minutes before drizzling the icing over the top. Let it set for another 10 minutes before serving.