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Keto Rhubarb Custard Pie

Keto rhubarb custard pie with a buttery almond flour crust and creamy sugar-free custard. Fresh rhubarb bakes into a lightly golden pie you slice clean after cooling.
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Prep Time 25 minutes
Cook Time 50 minutes
Cooling 3 hours
Total Time 4 hours 15 minutes
Servings: 8 servings
Course: Dessert
Cuisine: American
Calories: 430
Ingredients Equipment Method Notes

Ingredients
  

For crust
  • 2 cup almond flour
  • 0.25 cup butter melted
  • 2 tbsp erythritol
  • 1 egg
For filling
  • 3 cup fresh rhubarb diced
  • 1 cup erythritol or preferred keto sweetener
  • 3 egg
  • 0.25 cup heavy cream
  • 3 tbsp almond flour
  • 1 tsp vanilla extract
  • 0.125 tsp salt pinch

Equipment

  • 1 sheet pan
  • 1 Dutch oven

Method
 

Prepare & par-bake the crust
  1. Preheat the oven to 350°F and grease a 9-inch pie plate. Make sure the oven is fully heated so the crust sets on the first bake.
  2. Mix almond flour, melted butter, erythritol, and egg, then press the mixture into the pie plate. Press firmly to form an even crust layer.
  3. Bake the crust for 10 minutes at 350°F until it looks set. Remove it once the edges are starting to set.
Fill and bake
  1. Arrange the diced rhubarb in the baked crust. Distribute it evenly so each slice gets rhubarb.
  2. Whisk together erythritol, eggs, heavy cream, almond flour, vanilla extract, and salt until smooth. Keep whisking until no lumps of almond flour remain.
  3. Pour the custard mixture over the rhubarb. Tap the pie gently to help the custard settle into the fruit.
  4. Bake for 40 to 45 minutes at 350°F until the custard is set and lightly golden. Look for a gentle jiggle in the center rather than sloshing custard.
Cool and serve
  1. Cool the pie completely for at least 3 hours before slicing. Chilling time helps the custard fully set for clean slices.
  2. Refrigerate and serve chilled. Slice when cold for the firmest, creamy custard texture.

Notes

For the smoothest custard, whisk thoroughly until the almond flour dissolves, then pour promptly. Store covered in the refrigerator up to 4 days; freeze the whole pie only if you don’t mind a softer texture after thawing—custard can be less sliceable. For a lower-sugar profile, swap erythritol for another keto sweetener you prefer using a 1:1 ratio.