Keto southern boiled custard is the old-fashioned holiday drink — rich, pourable custard made from egg yolks, heavy cream, and vanilla, thickened slowly on the stove. Served ice-cold in mugs, it tastes like melted vanilla ice cream. The tempering step is where the smoothness is won.
Nothing says Christmas in the South quite like a warm mug of Boiled Custard. Growing up, it was a cherished tradition. My mamaw and her sister would whip up gallons of this liquid gold, and our family couldn’t get enough. This isn’t your typical spoon-and-bowl custard; it’s a rich, sippable drink, much like eggnog but traditionally served without the spirits. I was so excited to create this keto version to keep the tradition alive, especially for my dad who still adores this classic holiday treat.
Ingredients
• 5 large egg yolks
• ½ cup / 100g (3.5 oz) granular erythritol, divided
• 2 cups / 480ml heavy whipping cream
• 2 cups / 480ml water
• 2 tsp / 10ml vanilla powder or vanilla extract
Instructions
1. In a small bowl, vigorously whisk the egg yolks with ¼ cup of the erythritol until pale and slightly thickened. Set aside.
2. Attach a candy thermometer to the side of a large, heavy-bottomed pot. Pour in the heavy cream and water, then stir in the remaining ¼ cup of erythritol. Heat over medium, stirring occasionally, until the mixture is hot and the thermometer reads about 160°F (71°C). Do not let it boil.
3. To temper the eggs, ladle about ½ cup of the hot cream mixture into the egg yolk bowl while whisking constantly. This gently raises the temperature of the eggs without scrambling them. Slowly pour the tempered egg mixture back into the pot, whisking the entire time to combine.
4. Continue cooking over medium heat, stirring frequently and scraping the bottom of the pot, until the custard thickens and the thermometer reaches 180°F (82°C), which should take about 20 minutes. The custard is ready when it coats the back of a spoon.
5. Immediately remove the pot from the heat. Pour the custard through a fine-mesh strainer into a pitcher to catch any small bits of cooked egg. Stir in the vanilla. For rapid chilling, place the pitcher in an ice water bath. Otherwise, let it cool before refrigerating until thoroughly chilled. Serve cold in 8-ounce mugs or glasses. Store leftovers in an airtight container in the refrigerator for up to one week.
Nutritional Information
• Yield: 4 servings
• Serving Size: 1 cup (8 oz)
• Calories: 435
• Fat: 44g
• Protein: 5g
• Total Carbs: 3g (0.11 oz)
• Net Carbs: 3g (0.11 oz)
• Disclaimer: is an estimate and may vary.
Pro Tips
• for Perfect Custard
• For the most intense, authentic flavor, use vanilla powder. It won’t add the slight alcohol taste that extract can, resulting in a purer, creamier profile.
• Don’t skip the tempering step! Pouring the hot liquid into the eggs slowly and whisking constantly is crucial to prevent the eggs from scrambling.
• Always strain the finished custard through a fine-mesh sieve. This is a non-negotiable step for guaranteeing a perfectly silky-smooth texture.
• For a festive twist, add a cinnamon stick or a pinch of nutmeg to the cream and water mixture as it heats. Remove the spice before serving.
FAQ
Q: What is the difference between boiled custard and eggnog
A: Boiled custard is a rich, sippable Southern drink very similar to eggnog. The key difference is that traditional boiled custard is served without alcohol, offering a pure, creamy vanilla flavor.
Q: Why did my keto boiled custard curdle
A: Custard can curdle or scramble if the eggs are heated too quickly. To prevent this, it’s essential to temper the egg yolks by slowly whisking in about half a cup of the hot cream mixture before adding it all back to the pot. Also, do not let the custard reach a full boil.
Q: How do I know when the boiled custard is thick enough
A: The custard is ready when it has thickened enough to coat the back of a spoon. For best results, use a candy thermometer and cook, stirring frequently, until the mixture reaches 180°F (82°C).
Q: Can I make this boiled custard ahead of time
A: Absolutely. This recipe is perfect for making ahead. After cooking and chilling, store the custard in an airtight container in the refrigerator for up to one week. Serve it cold.
Pro Tips
- Temper properly: ladle about ½ cup of the hot cream mixture into the egg yolks while whisking constantly, then pour the tempered eggs back into the pot — this warms them without scrambling them.
- Use a candy thermometer and pull the custard at 180°F when it coats the back of a spoon; never let the cream and water mixture boil.
- For the most intense, authentic flavor, use vanilla powder instead of extract — it leaves out the slight alcohol note extract can carry.
- Always strain the finished custard through a fine-mesh sieve to catch any bits of cooked egg; it's the non-negotiable step for silky texture.
- Chill the pitcher quickly in an ice water bath, then refrigerate until cold and serve in 8-oz mugs. A cinnamon stick or pinch of nutmeg warmed with the cream makes a festive twist (remove before serving). Leftovers keep one week.
Frequently Asked Questions
Is boiled custard keto?
This version is — each of the four servings has 3 g of carbs with 44 g of fat from the heavy cream and egg yolks, sweetened with erythritol.
Why did my custard curdle or scramble?
The eggs hit the heat too fast. Temper them slowly with ladles of hot cream while whisking constantly, and never let the pot boil.
Can I make boiled custard ahead of time?
Yes — chill it thoroughly and store it in an airtight container in the refrigerator for up to one week. Serve it cold in mugs.
Why strain the custard through a sieve?
The fine-mesh strainer catches any small bits of cooked egg, guaranteeing the perfectly silky-smooth texture the drink is known for.
Recipe card below.
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Keto Southern Boiled Custard
Ingredients
Method
- In a small bowl, vigorously whisk the egg yolks with ¼ cup of the erythritol until pale and slightly thickened.
- Set aside.
- Attach a candy thermometer to the side of a large, heavy-bottomed pot.
- Pour in the heavy cream and water, then stir in the remaining ¼ cup of erythritol.
- Heat over medium, stirring occasionally, until the mixture is hot and the thermometer reads about 160°F (71°C).
- Do not let it boil.
- To temper the eggs, ladle about ½ cup of the hot cream mixture into the egg yolk bowl while whisking constantly. This gently raises the temperature of the eggs without scrambling them. Slowly pour the tempered egg mixture back into the pot, whisking the entire time to combine.
- Continue cooking over medium heat, stirring frequently and scraping the bottom of the pot, until the custard thickens and the thermometer reaches 180°F (82°C), which should take about 20 minutes. The custard is ready when it coats the back of a spoon.
- Immediately remove the pot from the heat.
- Pour the custard through a fine-mesh strainer into a pitcher to catch any small bits of cooked egg.
- Stir in the vanilla. For rapid chilling, place the pitcher in an ice water bath. Otherwise, let it cool before refrigerating until thoroughly chilled.
- Serve cold in 8-ounce mugs or glasses. Store leftovers in an airtight container in the refrigerator for up to one week.
- Don't skip the tempering step!
- Pouring the hot liquid into the eggs slowly and whisking constantly is crucial to prevent the eggs from scrambling.
