Strawberry Texas Sheet Cake

Ingredients

• Baking spray with flour
• 1 1/4 cups fresh strawberries, washed and quartered
• 1 (3-ounce) pkg. strawberry-flavored Jell-O, divided
• 1 (15.25-ounce) boxed white cake mix
• 3 tablespoon all-purpose flour
• 1 cup water
• 1/2 cup vegetable oil
• 2 large eggs, at room temperature and beaten
• 1/4 cup sour cream, at room temperature
• 1 teaspoon vanilla extract
• 2 cups powdered sugar, sifted
• 1/4 cup heavy whipping cream
• 1 teaspoon vanilla extract
• Slice fresh strawberries (optional)