Easy Jam Cake

Preheat the oven to 350°F. Spray a 9x13-inch baking pan with cooking spray.

Make the cake batter according to the package instructions. Combine the cake mix, eggs, water, and oil in a large mixing bowl and mix until completely combined, about 2 minutes at medium speed. Scrape the batter into the prepared pan.

Add the jam using spoonfuls from a tablespoon, evenly spaced and at least an inch from the edge of the pan. Take a butter knife and gently drag it through the spoonfuls in one direction, then the other. Be careful to only poke the knife about halfway down into the batter. Don't over-swirl or all of the jam will end up at the bottom of the cake.

Bake according to the package directions, until a toothpick inserted in the center (avoiding jam) comes out clean, 23 to 28 minutes. Move to a cooling rack and let cool completely before frosting, at least 1 hour.

Make the frosting: Add the butter to a medium mixing bowl and beat with a hand mixer on medium speed until very smooth and creamy, 1 to 2 minutes. Add the dulce de leche and salt and beat until well combined, about 1 minute. Scrape the bowl, then add the powdered sugar. Beat on low until combined, then increase the speed to medium and beat until creamy, 1 to 2 minutes. Spread the frosting on top of the cooled cake and serve. Store leftover cake at room temperature for up to a day or in the fridge for up to 5 days. Bring to room temperature before serving.