Summer Blueberry Cake - cooking recipe

Ingredients

Blueberry Filling
2 pints blueberries, divided
3/4 cup sugar
3 tablespoons water, divided
3 tablespoons cornstarch
2 tablespoons butter
1 teaspoon lemon zest
1 dash cinnamon
Cake
1 (18 1/4 ounce) package white cake mix (without pudding)
1/2 cup sour cream
1/2 cup whole milk
1/2 cup vegetable oil
3 large eggs
1 teaspoon vanilla extract
Topping
2 cups whipping cream
1 cup confectioners' sugar
1 teaspoon vanilla

Preparation

Make Filling: Put 1 cup of blueberries, sugar and 1 Tbsp water in a medium saucepan. Simmer over low heat until it becomes liquid. Mix remaining water and cornstarch and add to pan, cooking until it comes to a boil. Add the butter and cinnamon, stirring until the butter is melted, then add the rest of the blueberries. Cook for another minute, take off the heat and add the lemon zest. Set aside to cool.
Make Cake: Preheat the oven to 350 degrees. Grease and flour a 9\" x 13\" cake pan (or use a cooking spray with flour).
Put the cake mix, sour cream, milk, oil, eggs and vanilla in a large mixing bowl. Mix for 1 minute on low speed. Scrape down the bowl and mix on med-high speed for another 2 minutes.
Pour cake batter into the prepared pan. Using 1/2 of the blueberry filling, put dollops of the filling on the batter and swirl lightly with a knife. Bake the cake until it is light brown and starts to pull away from the sides of the pan, 35-40 minutes.
Cool cake and spread the rest of the blueberry filling on top.
Make frosting: Using chilled bowl and beaters, whip the cream until soft peaks form. Add vanilla, then the sugar while continung to beat until stiff peaks form.
Spread topping on cooled cake.
Serve with additional berries, if desired.