Preheat the oven to 350°F (175°C). Grease and flour the 9x13 inch baking pan.

In a large mixing bowl, combine the strawberry cake mix, eggs, sour cream, vegetable oil, and water. Beat with an electric mixer on medium speed until well combined, about 2 minutes.

Divide the batter in half. To one half, gently fold in the diced strawberries.

In another small bowl, mix together the brown sugar and cinnamon.

Pour half of the plain batter into the prepared baking pan. Sprinkle half of the brown sugar and cinnamon mixture over the batter. Next, spread the strawberry batter evenly over the top. Finally, pour the remaining plain batter over the strawberry layer and top with the remaining brown sugar and cinnamon mix.

Use a knife to swirl the batter gently.

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

Remove from the oven and let cool in the pan for 10 minutes, then transfer to a cooling rack to cool completely.

While the cake is cooling, prepare the strawberry cream icing. In a mixing bowl, beat the softened butter until creamy. Gradually add powdered sugar, mixing on low speed until combined.

Add the pureed strawberries, heavy cream, and vanilla extract. Beat until the icing is fluffy and smooth.

Once the cake is completely cooled, spread the strawberry cream icing evenly on top. Slice and serve.