Ingredients

Scale

For the Dump Cake:

1 can (14 oz) sweetened condensed milk
1 cup sour cream
½ cup freshly squeezed lemon juice (about 2–3 lemons)
1 tablespoon lemon zest (optional, for extra zing)
1 box yellow or lemon cake mix (15.25 oz)
1 stick (½ cup) unsalted butter, melted
1 can (21 oz) lemon pie filling or lemon curd (optional but recommended for added texture)

Optional Garnish:

Whipped cream
Lemon slices or zest
Powdered sugar
Crushed graham crackers

Instructions

Step 1: Preheat the Oven

Preheat your oven to 350°F (175°C). Lightly grease a 9×13-inch baking dish or spray it with nonstick cooking spray.

Step 2: Make the Lemon Filling

In a medium mixing bowl, whisk together sweetened condensed milk, sour cream, lemon juice, and lemon zest until fully combined. If you’re using lemon pie filling or curd, fold it into the mixture now.

Step 3: Dump the Layers

Pour the lemon mixture into the bottom of the prepared baking dish, spreading it evenly.
Evenly sprinkle the dry cake mix over the lemon mixture — do not stir.

Step 4: Add the Butter

Drizzle the melted butter over the top of the dry cake mix. Make sure most of the surface is covered in butter. Gaps are okay; they’ll fill in during baking.

Step 5: Bake to Golden Perfection

Place the dish in the oven and bake for 45–50 minutes, or until the top is golden brown and the edges are bubbling.
Let it cool at room temperature, then refrigerate for at least 2 hours for best texture.

Notes

This is a “dump cake”, so mixing is minimal. Don’t overthink it — just dump and bake.
The lemon filling thickens naturally as it bakes and chills, mimicking the texture of lemon icebox pie.
Let the cake cool completely before refrigerating to avoid a soggy bottom.