These 3-ingredient lemon bars are sweet, tart, buttery, and wonderfully easy, with a soft lemon filling tucked between a simple crust and crumbly golden topping. Made with lemon cake mix, butter, and canned lemon pie filling, they’re perfect when you need a crowd-pleasing dessert without the fuss. You’re going to love how quickly they come together and how well they travel once chilled.
Why You’ll Love It
- Just three ingredients — no extra vanilla, salt, powdered sugar, or special garnish required.
- No mixer needed — the buttery cake mix becomes both the crust and crumbly topping.
- Bright lemon flavor — canned lemon pie filling gives these bars their glossy, familiar tang.
- Easy to share — chill and cut into small squares for a crowd.
Ingredient Notes
Use a lemon cake mix in the 15.25- to 16.5-ounce range. I usually grab whatever is on sale — store brand, it truly doesn’t matter much. Just make sure it’s lemon cake mix, not lemon pudding mix or one of those boxes with a dozen extra packets tucked inside. We are keeping this easy. Try our 2-Ingredient Lemon Bars next.
The butter should be unsalted and melted, then allowed to cool slightly. Not cold, obviously, but don’t pour it in while it’s sputtering-hot either. I did that once when I was in a hurry and got a few odd little dough pebbles. They baked up fine, because this recipe is forgiving, but it annoyed me anyway.
For the lemon pie filling, use one 21-ounce can. Lemon pie filling, not lemon curd. Lemon curd is lovely, but it is not what we’re doing here, and it can be expensive enough to make you stare at the receipt in the parking lot. The canned filling has that bright, familiar tang that makes these bars taste like they came from somebody’s old-fashioned recipe box — in a good way. If you like this, you'll love our 5-Ingredient Slow Cooker Lemon Lush with Yellow Cake Mix.
And yes, you really do bake these in a glass 9-by-13-inch dish. I prefer a clear one because you can see the lemon layer, plus it’s easier to tell when the edges are bubbling.
Ingredients
- 1 box lemon cake mix, 15.25 to 16.5 ounces — dry, straight from the box
- 1/2 cup unsalted butter, melted and slightly cooled — that’s 1 stick
- 1 can (21 ounces) lemon pie filling
Instructions
Preheat your oven to 350°F. Lightly grease a clear 9×13-inch glass baking dish with butter or nonstick spray. I usually use spray because it’s faster, though butter does make me feel like I have my life together for roughly thirty seconds.
Pour the dry lemon cake mix into a medium mixing bowl. Add the melted, slightly cooled butter and stir with a fork or spatula until every bit of cake mix is moistened. You’re looking for soft, damp crumbs, sort of like wet sand at the edge of the lake — not a smooth dough. Keep stirring until there are no dry floury patches hiding in the bottom of the bowl.
Press about two-thirds of the buttery cake mixture into the bottom of the prepared baking dish. Use your fingertips or the bottom of a measuring cup to make it even and fairly firm, getting into the corners. Don’t obsess over it being perfect; I have spent too much of my life trying to make things look perfect, and it has rarely improved dessert.
Spoon the entire can of lemon pie filling over the crust. Spread it gently with the back of a spoon or an offset spatula until it reaches from edge to edge. Try not to dig into the crust underneath, because then the layers get muddled. They will still taste good — this is lemon and butter, not a chemistry final — but the pretty yellow middle is nicer when it stays put.
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Sprinkle the remaining one-third of the cake-and-butter crumbs evenly over the lemon filling. Let the crumbs fall naturally in little clumps. Do not press them down. That loose, craggy top is what turns lightly golden and gives you those buttery bits everybody picks at while the pan is cooling. For another easy option, see our Slow Cooker 4-Ingredient Key Lime Cake.
Place the dish on the center rack of the oven and bake for 25 to 30 minutes. The topping should be lightly golden in places, and the lemon filling should bubble gently around the edges. The center will still seem soft, which is normal. Do not keep baking until it looks firm as a sidewalk — I made that mistake once and the bars were still edible, but they had the texture of a very determined sponge.
Remove the pan from the oven and set it on a cooling rack. Let the bars cool completely in the glass dish so the lemon layer has time to set. I know this is the annoying part. They are delicious warm, but they scoop more than slice at that point.
For cleaner squares, refrigerate the cooled bars for at least 1 to 2 hours before cutting. Use a sharp knife to cut them into 16 squares, or go smaller if you’re setting them out with other desserts. Wipe the knife between cuts if you want tidy edges. For everyday serving, they’re still delicious without perfectly tidy edges.
Serve the bars chilled or at room temperature, straight from the glass dish if you like. A cup of coffee or black tea alongside is awfully good, especially after a heavy meal. They don’t need whipped cream, though nobody has ever complained when it appeared.
Variations
If you want a less sweet bar, you can use a yellow or white cake mix instead of lemon cake mix. You still get plenty of citrus from the pie filling, but the overall flavor is softer and more buttery.
For a sharper lemon flavor, stir 1 to 2 tablespoons of freshly squeezed lemon juice and a little finely grated lemon zest into the canned filling before spreading it over the crust. I like this version in the spring, when everyone starts pretending they have the energy to clean windows.
You can also stir 1/2 cup unsweetened shredded coconut or finely chopped toasted almonds into the cake-and-butter crumbs.
A dusting of powdered sugar over cooled bars looks pretty on a holiday table. I will say, though, powdered sugar has a way of finding the black sweater you swore you weren’t going to wear while cooking. It’s practically attracted to it. You might also like our 4-Ingredient Lemon Cream Cheese Dump Cake.
For another lemon dessert, Lemon Meringue Pie has a tart cooked filling and a tall, toasted meringue.
For a creamy lemon dessert, try Lemon Cheesecake Bars with their graham cracker crust.
Storage & Reheating
Keep leftover lemon bars covered in the refrigerator. They’ll hold nicely for about 3 to 4 days, though I have rarely had a full pan last that long. The topping softens a little after the first day, but the flavor is still wonderful — maybe even better, actually. So there, I contradicted myself. I like them fresh, but I also like them the next day.
You don’t need to reheat these. They are best chilled or brought to room temperature for a few minutes before serving. If you leave them sitting out for dinner, they’ll be fine for the evening, but I put leftovers back in the refrigerator once everyone has stopped wandering through the kitchen.
If I’m taking them somewhere, I chill the whole pan first, then cover it tightly.
Final Notes
There’s something comforting about a dessert that doesn’t ask much of you. No separating eggs, no watching a candy thermometer like it owes you money, no fancy garnish that gets limp the second you put it on the table. Just a cake mix, butter, lemon filling, and a little patience while it cools. Try our Southern 3-Ingredient Cheddar Biscuit Bites next.
These are especially useful when life feels busy. Bright lemon, buttery crumbs, and a dessert that disappears quickly… not a bad little thing to be known for. If you like this, you'll love our Caramel Brownie Cheesecake.
3-Ingredient Lemon Bars
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Ingredients
- 1 box lemon cake mix 15.25 to 16.5 ounces; dry, straight from the box
- 1/2 cup unsalted butter melted and slightly cooled; 1 stick
- 1 can lemon pie filling 21 ounces
Instructions
- Preheat the oven to 350°F and lightly grease a clear 9x13-inch glass baking dish with butter or nonstick spray.
- Pour the dry lemon cake mix into a medium mixing bowl, add the melted and slightly cooled butter, and stir with a fork or spatula until all the cake mix is moistened and soft, damp crumbs form with no dry patches.
- Press about two-thirds of the buttery cake mixture evenly and fairly firmly into the bottom of the prepared baking dish, reaching into the corners.
- Spoon the entire can of lemon pie filling over the crust and gently spread it from edge to edge without digging into the crust.
- Sprinkle the remaining one-third of the cake-and-butter crumbs evenly over the lemon filling without pressing them down.
- Place the dish on the center oven rack and bake for 25 to 30 minutes, until the topping is lightly golden in places and the lemon filling bubbles gently around the edges.
- Remove the pan from the oven and let the bars cool completely in the glass dish on a cooling rack so the lemon layer can set.
- Refrigerate the cooled bars for at least 1 to 2 hours, then use a sharp knife to cut them into 16 squares, wiping the knife between cuts for cleaner edges.
- Serve the bars chilled or let them stand at room temperature for a few minutes before serving.
Notes
Nutrition
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Nutrition values are estimates based on the listed ingredients and serving count. Actual values vary with brands, cuts and portion sizes.
