Preheat the oven to 350℉. Spray a 9x13-inch cake pan with cooking spray. Set aside.
In a large bowl using a hand mixer, or use the bowl of a stand mixer with the paddle attachment, add the dry cake mix, eggs, water, and melted butter. Beat on medium-high speed for 2 minutes, or until the batter lightens in color and is thoroughly combined.
1 box (13.25 oz) strawberry cake mix, 3 large eggs, 1 cup water, 1/2 cup (1 stick) salted butter
Pour the strawberry cake batter into the prepared cake pan.
Bake for 35-40 minutes or until a toothpick inserted in the center of the cake comes out clean.
Allow the cake to cool to room temperature before continuing - about 30 minutes.
Poke holes over the whole cake with a fork.
In a medium bowl, whisk together the sweetened condensed milk, evaporated milk, and whole milk. Slowly pour the milk mixture over the cake, allowing it to be absorbed into the fork holes as you pour it slowly.
1 can (14 oz) sweetened condensed milk, 1 can (12 oz) evaporated milk, 1 cup whole milk
Cover the cake with a lid, plastic wrap, or foil and refrigerate it for at least 8 hours or overnight.
Add the fresh sliced strawberries and granulated sugar into an airtight container. Refrigerate the strawberries along with the cake.
1 pound fresh strawberries, 2 tablespoons granulated sugar
When ready to serve, beat the heavy cream, powdered sugar, and vanilla extract until soft peaks form (start at low speed and increase the speed as needed). Spread the whipped cream over top of the milk-soaked cake.
1½ cup heavy whipping cream, 1/4 cup powdered sugar, 1 teaspoon vanilla extract
Top the whipped cream with the sliced strawberries and their juices (from the fridge). Serve & enjoy!