This easy Deep South Strawberry Cake has a secret, but we won't tell

Reprinted with permission from A New Take on Cake by Anne Byrn copyright © 2021. Photographs by Danielle Atkins. Published by Clarkson Potter, a division of Penguin Random House, LLC.
About the recipe
If you visit bakeries, diners, and home kitchens in the South, you will find this cake —bright pink and packed with strawberry flavor. It comes at that flavor both honestly (with fresh strawberries) and maybe not so much (with strawberry-flavored gelatin) — but who’s to tell?
Half a package of strawberry gelatin adds plenty of strawberry flavor and color in this cake if you'd like to reduce sugar. Save the remainder for another cake!
Serves 12
Prep: 35-40 minutes
Bake time: 25-30 minutes
Ingredients
For the cake:
Vegetable oil spray or shortening, for greasing the pans
All-purpose flour, for dusting the pans
1 (15.25-ounce) package yellow or butter cake mix
1/3 cup all-purpose flour
1 (3-ounce) package strawberry gelatin
3 large eggs
1 cup mashed fresh strawberries (from 1½ cups hulled sliced berries)
1/2 cup vegetable oil
1/2 cup whole milk
For the frosting:
3 ounces strawberries
4 ounces cream cheese, at room temperature
4 tablespoons (½ stick) unsalted butter, at room temperature
½ teaspoon vanilla extract
Pinch of salt
3 cups confectioners’ sugar, sifted
Assembly:
Strawberry Cream Cheese Frosting (recipe follows)
1 whole strawberry, for garnish
Instructions
Make the cake:
Place a rack in the center of the oven and preheat the oven to 350°F. Grease and flour two 9-inch round cake pans. Set the pans aside.
In a large mixing bowl, stir together the cake mix, flour, and gelatin. Add the eggs, strawberries, oil, and milk. Beat with an electric mixer on low speed until blended, about 30 seconds.
Stop the machine and scrape down the sides of the bowl with a rubber spatula. Increase the mixer speed to medium and beat for 1 minute, until well blended. Divide the batter evenly between the prepared pans, smoothing it out with a rubber spatula.
Place the pans in the oven and bake until the cakes are lightly browned and spring back when gently pressed in the middle, 25 to 30 minutes.
Let the cakes cool in the pans on wire racks for 10 to 15 minutes. Run a dinner knife around the edge of each pan, then invert each layer onto a rack. Invert the layers again so they are right-side up and allow the cakes to cool completely, about 20 minutes longer.
Make the frosting:
Strain the puree through a fine-mesh sieve to remove the seeds to yield 1½ to 2 tablespoons strained puree. Set aside.
In a medium mixing bowl, combine the cream cheese and butter and beat with an electric mixer on low speed until creamy, about 30 seconds.
Add the strawberry puree, vanilla, salt and 2 1/2 cups of the confectioners’ sugar and beat with the mixer on low until smooth, about 1 minute.
Add the remaining 1/2 cup sugar, increase the mixer to medium, and beat until fluffy, about 1 minute.
Frost your cake as desired, or store, covered, in the refrigerator for up to two days. Let the frosting come to room temperature before using.
Assemble the cake:
Place one cake layer, right-side up, on a cake plate and spread 3/4 cup frosting over the top.
Place the second cake layer, right-side up, on top of the first. Spread some of the frosting smoothly over the top.
Frost the sides of the cake with the remaining frosting, first applying a thin “crumb coat” to seal in the cake crumbs and then adding a second, more generous layer of frosting. (If desired, pull the frosting off the sides of the cake for a barely naked look.) Place the whole strawberry on top.
Slice and serve.
Store, lightly covered, in the refrigerator for up to four days.