Strawberry Swirl Coffee Cake

Name: Strawberry Swirl Coffee Cake
Cuisine: American
Ingredients: 1 cup of frozen strawberry puree, defrosted (no sugar added); 1/4 cup granulated sugar; 1 TBS cornstarch, dissolved in 1 TBS water; 1 tsp. unsalted butter; 5 TBS unsalted butter, room temperature; 3/4 cup granulated sugar; 1 large egg, room temperature; 1/2 tsp. pure vanilla extract; 2 cups all purpose flour; 1 1/2 tsp. baking powder; 1/2 tsp. baking soda; 1/2 tsp. kosher salt; 1/2 tsp. ground cinnamon; 1 cup buttermilk; 1/2 cup all purpose flour; 1/2 cup granulated sugar; 1/2 tsp. cinnamon; 1/4 tsp. kosher salt; 6 TBS unsalted butter, cut into cubes, cold