Quick Recipe Version (TL;DR)

Yield: 16 bars
Prep Time: 25 minutes
Cook Time: 55 minutes
Total Time: About 2 hours 15 minutes (including cooling)

Quick Ingredients

2 cups (240 g) all-purpose flour, plus 1/2 cup (60 g) for custard
1/2 cup (100 g) granulated sugar for crust
1 1/2 cups (300 g) granulated sugar for custard
1/4 teaspoon fine sea salt for crust + 1/2 teaspoon for custard
1 cup (226 g) cold unsalted butter, cubed
4 cups diced rhubarb (about 1 1/4 lb trimmed)
4 large eggs
1 cup heavy cream
1/2 cup whole milk
1 teaspoon vanilla extract
Powdered sugar, for dusting (optional)

Do This

1. Heat oven to 350°F (175°C). Grease a 9×13-inch baking pan and line with parchment.
2. Mix 2 cups flour, 1/2 cup sugar, and 1/4 teaspoon salt; cut in cold butter until crumbly. Press evenly into pan.
3. Bake crust 15–18 minutes until just set and lightly golden at the edges.
4. While crust bakes, whisk eggs, 1 1/2 cups sugar, 1/2 cup flour, 1/2 teaspoon salt, vanilla, cream, and milk until smooth.
5. Spread diced rhubarb evenly over hot crust. Slowly pour custard over rhubarb.
6. Bake 35–40 minutes, until custard is just set with a slight jiggle in the center and edges are lightly golden.
7. Cool completely, chill 30–60 minutes for clean slices, dust with powdered sugar, and cut into bars.

Why You’ll Love This Recipe

Old-fashioned Amish comfort: simple ingredients baked into a cozy, farmhouse-style dessert.
Irresistible contrast: buttery shortbread-style crust, silky vanilla custard, and tart rhubarb in every bite.
Great for gatherings: bakes in a 9×13-inch pan and slices cleanly into easy-to-serve bars.
Make-ahead friendly: tastes even better chilled and holds beautifully in the fridge.

Grocery List

Produce: Fresh rhubarb (about 1 1/4 lb, to yield 4 cups diced)
Dairy: Unsalted butter, heavy cream, whole milk, eggs
Pantry: All-purpose flour, granulated sugar, powdered sugar (optional, for dusting), vanilla extract, fine sea salt

Full Ingredients

For the Shortbread-Style Crust

2 cups (240 g) all-purpose flour, spooned and leveled
1/2 cup (100 g) granulated sugar
1/4 teaspoon fine sea salt
1 cup (226 g) cold unsalted butter, cut into small cubes

For the Rhubarb Custard Layer

4 cups fresh rhubarb, diced into 1/2-inch pieces (about 1 1/4 lb trimmed stalks)
4 large eggs, at room temperature if possible
1 1/2 cups (300 g) granulated sugar
1/2 cup (60 g) all-purpose flour
1/2 teaspoon fine sea salt
1 teaspoon pure vanilla extract
1 cup heavy cream
1/2 cup whole milk

For Serving (Optional)

Powdered sugar, for dusting
Thinly sliced rhubarb ribbons or small mint leaves, for garnish

Step-by-Step Instructions

Step 1: Prepare the Pan and Preheat the Oven

Preheat your oven to 350°F (175°C) with a rack in the center position. Lightly grease a 9×13-inch (23×33 cm) baking pan with butter or nonstick spray.

For the easiest removal and neatest bars, line the pan with a sheet of parchment paper, leaving a bit of overhang on the long sides to create “handles.” Lightly grease the parchment as well. Set the pan aside while you make the crust.

Step 2: Make the Shortbread-Style Crust

In a mixing bowl, combine the 2 cups flour, 1/2 cup sugar, and 1/4 teaspoon salt. Stir to distribute the sugar and salt evenly through the flour.

Add the cold, cubed butter. Using a pastry cutter, two knives, or your fingertips, cut or rub the butter into the dry ingredients until the mixture looks like coarse crumbs with some pea-sized bits of butter remaining. The crumbs should hold together when pressed between your fingers.

Tip the crumbly mixture into the prepared pan. Press it firmly and evenly over the bottom, paying special attention to the corners. A flat-bottomed measuring cup works well for pressing the crust into a tight, even layer. Do not build the crust up the sides; keep it in a flat, even slab on the bottom only.

Step 3: Par-Bake the Crust

Place the pan in the preheated oven and bake for 15–18 minutes, or until the crust is just set and the very edges are starting to turn a light golden color. The surface may look slightly dry but should not be deeply browned.

While the crust is baking, start preparing the rhubarb and custard so everything is ready when the crust comes out of the oven. This helps the custard soak in just enough while the crust is still hot.

Step 4: Prep the Rhubarb and Make the Custard

Rinse the rhubarb stalks under cool water and pat dry. Trim off any leaves (they are toxic and should be discarded) and tough ends. Slice the stalks into 1/2-inch pieces to make 4 cups. Set aside.

In a large bowl, whisk the eggs until well combined. Add the 1 1/2 cups sugar, 1/2 cup flour, and 1/2 teaspoon salt. Whisk until the mixture is smooth and no dry streaks of flour remain, scraping the sides and bottom of the bowl as needed.

Whisk in the vanilla extract, then slowly add the heavy cream and milk, whisking constantly, until the custard is silky and well blended. It will be pourable and slightly thickened from the flour. If you see any small lumps, give it an extra 20–30 seconds of firm whisking.

Step 5: Layer Rhubarb and Pour the Custard

When the crust finishes par-baking, remove the pan from the oven but leave the oven on. Working quickly while the crust is hot helps the layers meld together.

Evenly scatter the diced rhubarb over the hot crust, spreading it all the way to the edges and into the corners so every bar gets a good amount of fruit.

Stir the custard mixture once more, then slowly pour it over the rhubarb-covered crust. Pour gently and evenly so the rhubarb stays distributed rather than clumping to one side. The custard will look quite liquid at this stage—that is correct.

Step 6: Bake Until the Custard Is Just Set

Carefully return the pan to the oven and bake at 350°F (175°C) for 35–40 minutes. The bars are done when the edges are lightly golden and puffed, and the center looks set around the edges but still has a very slight, gentle jiggle when you nudge the pan.

If you insert a knife or toothpick about 2 inches in from the edge, it should come out mostly clean, though it may have a bit of custard on it. Avoid overbaking, or the custard can become rubbery and lose its silky texture.

If the edges are browning too quickly before the center is set, loosely tent the pan with foil for the last 5–10 minutes of baking.

Step 7: Cool, Chill, and Slice into Bars

Remove the pan from the oven and place it on a wire rack. Let the bars cool in the pan at room temperature until no longer warm to the touch, about 1 hour.

For the cleanest slices and best texture, transfer the cooled pan to the refrigerator and chill for at least 30–60 minutes. Once chilled, use the parchment overhang to lift the entire slab out of the pan onto a cutting board.

Dust the top lightly with powdered sugar, if using. Using a sharp knife, cut into 16 squares (4 rows by 4 rows), wiping the knife with a warm, damp cloth between cuts for tidy edges. Garnish individual bars with a tiny rhubarb ribbon or mint leaf if you like, and serve slightly chilled or at cool room temperature.

Pro Tips

Use only the stalks. Rhubarb leaves are toxic and should be discarded; trim them off completely and use only the crisp, colorful stalks.
Keep the butter cold. Cold butter is essential for a tender, shortbread-like crust. If your kitchen is warm, pop the crust mixture in the fridge for 5–10 minutes before pressing into the pan.
Do not overbake the custard. Pull the bars when the center still has a slight wobble; they will finish setting as they cool and stay creamy instead of firm and rubbery.
Chill before cutting. A brief chill in the fridge makes the custard layer stable and easy to slice into neat squares.
Balance the tartness. If your rhubarb is especially sour, you can sprinkle an extra 1–2 tablespoons of sugar over the rhubarb before pouring on the custard.

Variations

Strawberry-Rhubarb Custard Bars: Replace 1–1 1/2 cups of the rhubarb with sliced fresh strawberries for a softer, sweeter flavor and a lovely pink hue.
Cinnamon Sugar Top: During the last 10 minutes of baking, sprinkle 2 tablespoons sugar mixed with 1/2 teaspoon ground cinnamon over the surface for a lightly crackly, spiced finish.
Nutty Crust Twist: Substitute 1/2 cup of the crust flour with finely chopped pecans or walnuts for a toasty, nutty base that pairs beautifully with the custard.

Storage & Make-Ahead

Once fully cooled, store the rhubarb custard bars in an airtight container in the refrigerator for up to 4 days. Layer the bars with parchment paper if stacking to prevent sticking. These bars are an excellent make-ahead dessert: you can bake them the day before, chill overnight, and slice right before serving.

For longer storage, you can freeze the cut bars on a baking sheet until firm, then transfer to a freezer-safe container with parchment between layers. Freeze for up to 2 months. Thaw in the refrigerator overnight, then dust with fresh powdered sugar just before serving to refresh their appearance.

Nutrition (per serving)

Approximate values per bar (1 of 16): about 280 calories, 13 g fat, 38 g carbohydrates, 1 g fiber, 25 g sugars, and 4 g protein. Actual values will vary based on specific ingredients and serving size.

Amish Rhubarb Custard Bars on Buttery Shortbread