Keto Rhubarb Lemon Meringue Squares from Grandma’s Kitchen

Keto Rhubarb Lemon Meringue Squares: a refined, low-carb dessert that highlights tart rhubarb. The base is a moist, lemon-scented almond cake, the center a sweet-tangy rhubarb custard, and the top a light, fluffy meringue.

Don’t be intimidated by the three layers — this dessert is straightforward and yields an impressive result. It began as a family recipe called “Spring Rhubarb Dessert” from my grandmother’s collection. Titled “Art’s favorite dessert,” it immediately won over my family. My sister and even my picky 21-year-old son loved it. I adapted it to be keto-friendly while keeping the bright lemon and rhubarb flavors intact.

Can I Eat Rhubarb on Keto?

Rhubarb is technically a vegetable, though it’s commonly used in sweet dishes like pies and crumbles. Nutritionally, it’s keto-compatible: one cup of diced rhubarb contains about 26 calories and roughly 3.3 net carbs, making it a great option for low-carb desserts.

Gather These Items for this Low Carb Rhubarb Dessert Recipe

Food ingredients:

Rhubarb (sliced)
Lemons (zest and juice)
Almond flour
Zero-carb sweetener (monk fruit or equivalent)
Eggs
Butter

Tools and equipment:

Lemon zester or microplane
Electric mixer for whipping egg whites
Pot or saucepan
Mixing bowls
9 x 13-inch baking pan

Tips and Tricks for Making Keto Rhubarb Lemon Meringue Squares

If you prefer, the original recipe used orange juice and zest; I substituted two lemons with great results. Either citrus works—lemon offers a brighter tang.
You can prepare the rhubarb custard a day ahead and refrigerate it to speed assembly on baking day.
If you don’t have cream of tartar, the meringue can still turn out well without it, though cream of tartar helps stabilize the egg whites.
After baking, cool completely and then refrigerate. Chilling allows the lemon flavor to soak into the base, creating a moist, flavorful square.
If you use a different sweetener, adjust sweetness to taste. The original (non-keto) version used larger amounts of sugar; this keto adaptation reduces those quantities to keep carbs low.

Keto Rhubarb Lemon Meringue Squares Recipe

Keto Rhubarb Lemon Meringue Squares

Yield:
24

Prep Time:
15 minutes

Cook Time:
30 minutes

Total Time:
45 minutes

Bottom: lemony almond base. Middle: sweet-tart rhubarb custard. Top: feather-light meringue.

Ingredients

Bottom Layer

1 1/2 cups almond flour
1/4 cup sweetener
1/2 cup softened butter

Filling

4 cups sliced rhubarb
2 tbsp butter
1 cup sweetener
Zest and juice of 2 lemons
3 egg yolks, beaten (reserve whites)

Topping

3 egg whites
1/4 cup sweetener
1/2 tsp cream of tartar (optional)

Instructions

Preheat oven to 350°F (175°C). In a bowl, blend almond flour, 1/4 cup sweetener, and softened butter until well combined. Press evenly into the bottom of a 9 x 13-inch pan.
Bake the crust for 10 minutes until set and slightly golden.
While the crust bakes, prepare the filling: in a saucepan combine sliced rhubarb, lemon zest and juice, butter, and 1 cup sweetener. Bring to a boil, then reduce heat and simmer until the rhubarb softens and the mixture thickens slightly.
Remove from heat and temper in the beaten egg yolks, stirring quickly to incorporate so the yolks do not scramble. Spread the rhubarb custard over the pre-baked crust.
Whip the reserved egg whites with 1/4 cup sweetener and cream of tartar (if using) until stiff peaks form. Spread the meringue over the rhubarb layer, covering to the edges.
Return to the oven and bake at 350°F (175°C) for 15–20 minutes, or until the meringue is a light golden color.
Cool completely, then refrigerate until chilled. Cut into squares and serve cold for best texture and flavor.

Notes

The non-keto original used larger amounts of granulated sugar: more sugar in the custard and a bit in the crust and meringue. This keto version reduces those amounts and substitutes zero-carb sweetener to keep net carbs low. Adjust sweetness to taste.