Keto Lemon Custard – Bright, Creamy, And Low-Carb
This Keto Lemon Custard brings a sunny burst of flavor to your dessert routine without loading up on sugar. It’s silky, smooth, and gently tangy—perfect for anyone craving something light but satisfying. You’ll only need simple ingredients, a few steps, and a little patience.
Serve it chilled for a refreshing treat, or dress it up with berries. Either way, this is a dessert you’ll want on repeat.
Ingredients
Method
- Preheat and prep. Heat your oven to 325°F (160°C). Place 4–6 small ramekins in a deep baking dish. Boil a kettle of water for the water bath.
- Warm the cream. In a small saucepan, gently heat 1 1/2 cups heavy cream over low heat until warm to the touch but not simmering. Remove from heat. If using, whisk in 1 tablespoon unsalted butter until melted.
- Mix the lemon base. In a bowl, whisk 1/2 cup granulated erythritol or allulose with a pinch of salt, the finely grated zest of 1 lemon, and 3 large eggs until smooth. Whisk in 1 teaspoon vanilla extract and 2–3 tablespoons fresh lemon juice (adjust to taste).
- Temper the eggs. Slowly stream the warm cream into the egg mixture while whisking constantly. This prevents scrambling and creates a silky texture.
- Strain for smoothness. Pour the custard through a fine-mesh sieve into a large measuring cup or bowl to catch any zest clumps or egg bits. This step makes the custard extra smooth.
- Fill the ramekins. Divide the custard evenly among the ramekins. Tap them gently to release any surface bubbles.
- Make a water bath. Slide the baking dish into the oven. Carefully pour hot water into the dish until it reaches halfway up the sides of the ramekins.
- Bake until just set. Bake 25–35 minutes, depending on ramekin size. The centers should jiggle slightly when nudged but not slosh. Do not overbake or the custard may curdle.
- Cool gradually. Remove the ramekins from the water bath and let them cool on a rack. Chill for at least 2 hours, or overnight for best flavor and texture.
- Serve. Enjoy plain, or add a few fresh berries and a light sprinkle of lemon zest. A tiny dollop of whipped cream is a nice touch if it fits your macros.
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What Makes This Special
This custard has the classic lemon flavor you love, but it stays low-carb by using a keto-friendly sweetener. It’s baked gently in a water bath, which gives it a restaurant-quality texture—soft, creamy, and set just right.
The recipe uses whole eggs and cream for richness, with lemon zest and juice for a clean citrus finish. It’s easy enough for a weeknight and pretty enough for guests.
Shopping List
- Heavy cream (or canned full-fat coconut milk for dairy-free)
- Eggs (large)
- Granulated erythritol or allulose (or a keto-friendly blend)
- Fresh lemons (zest and juice)
- Vanilla extract
- Unsalted butter (optional, for extra silkiness)
- Pinch of salt
- Fresh berries (optional garnish)
Step-by-Step Instructions
- Preheat and prep. Heat your oven to 325°F (160°C). Place 4–6 small ramekins in a deep baking dish.
Boil a kettle of water for the water bath.
- Warm the cream. In a small saucepan, gently heat 1 1/2 cups heavy cream over low heat until warm to the touch but not simmering. Remove from heat. If using, whisk in 1 tablespoon unsalted butter until melted.
- Mix the lemon base. In a bowl, whisk 1/2 cup granulated erythritol or allulose with a pinch of salt, the finely grated zest of 1 lemon, and 3 large eggs until smooth.
Whisk in 1 teaspoon vanilla extract and 2–3 tablespoons fresh lemon juice (adjust to taste).
- Temper the eggs. Slowly stream the warm cream into the egg mixture while whisking constantly. This prevents scrambling and creates a silky texture.
- Strain for smoothness. Pour the custard through a fine-mesh sieve into a large measuring cup or bowl to catch any zest clumps or egg bits. This step makes the custard extra smooth.
- Fill the ramekins. Divide the custard evenly among the ramekins.
Tap them gently to release any surface bubbles.
- Make a water bath. Slide the baking dish into the oven. Carefully pour hot water into the dish until it reaches halfway up the sides of the ramekins.
- Bake until just set. Bake 25–35 minutes, depending on ramekin size. The centers should jiggle slightly when nudged but not slosh. Do not overbake or the custard may curdle.
- Cool gradually. Remove the ramekins from the water bath and let them cool on a rack.
Chill for at least 2 hours, or overnight for best flavor and texture.
- Serve. Enjoy plain, or add a few fresh berries and a light sprinkle of lemon zest. A tiny dollop of whipped cream is a nice touch if it fits your macros.
Keeping It Fresh
This custard keeps well in the fridge for 3–4 days. Cover each ramekin tightly to prevent absorbing fridge odors and to keep the top from drying out.
For the best texture, store it plain and add toppings right before serving. If condensation forms, gently blot the surface with a paper towel before garnishing.
Benefits of This Recipe
- Keto-friendly and low-carb: Uses erythritol or allulose instead of sugar, keeping total carbs in check.
- Protein and fats for satiety: Eggs and cream make this dessert satisfying, helping you avoid sugar spikes.
- Simple ingredients: No special equipment beyond basic kitchen tools and some ramekins.
- Customizable flavor: Adjust lemon intensity, sweetness, and garnishes without changing the method.
- Make-ahead friendly: Ideal for meal prep or entertaining—set them the day before.
Pitfalls to Watch Out For
- Overbaking: If the custard is baked until fully firm, it can turn grainy. Pull it when the center still has a gentle wobble.
- Skipping the water bath: Dry heat can cause curdling.
The water bath ensures even, gentle cooking.
- Too much lemon juice: Acid is great, but too much can tighten the custard. Start with 2 tablespoons, then adjust next time.
- Sweetener choice: Erythritol can crystallize slightly as it chills. Allulose stays smoother but can brown faster; watch your bake time.
- Hot cream shock: Pouring very hot cream directly into eggs can scramble them.
Warm, not boiling, is the sweet spot.
Recipe Variations
- Dairy-free: Use full-fat coconut milk instead of cream and skip the butter. Add an extra pinch of salt to balance sweetness.
- Meyer lemon: Swap in Meyer lemons for a sweeter, floral twist; you may reduce sweetener slightly.
- Lavender lemon: Steep 1/2 teaspoon culinary lavender in the warm cream for 10 minutes, then strain before tempering.
- Lemon-vanilla bean: Use the seeds from half a vanilla bean for a luxurious aroma and pretty specks.
- Lemon-lime: Use half lemon, half lime juice and zest for a brighter, punchier citrus profile.
- Lemon posset style: For an even simpler no-bake vibe, simmer cream with sweetener to reduce slightly, then stir in lemon juice and chill. Note: texture differs from custard but still keto-friendly if sweetener is low-carb.
FAQ
Can I use bottled lemon juice?
Fresh juice delivers cleaner flavor and better aroma.
Bottled juice can taste flat or harsh, but in a pinch, it will work. Add extra zest to boost freshness.
What sweetener works best?
Allulose gives the smoothest texture and least cooling effect. Erythritol blends are fine but may crystallize slightly after chilling.
Start with the listed amount and adjust to your taste next time.
How do I know when it’s done?
The edges should look set, and the center should wobble gently when you nudge the ramekin. If it’s fully firm in the center, it’s overbaked.
Can I make one large custard instead of ramekins?
Yes. Use a 1-quart baking dish and extend the bake time to 40–55 minutes, checking for that slight jiggle in the center.
Keep the water bath at the same level.
Is this safe for a strict keto diet?
Yes, provided you use a keto-friendly sweetener and account for the small amount of carbs from lemon. Portion size and sweetener choice can help you stay within your macros.
Why did my custard curdle?
Likely the oven was too hot, you skipped the water bath, or the cream was added too hot to the eggs. Straining helps, but gentle heat is the key.
Can I freeze it?
Freezing changes the texture and can make it watery when thawed.
It’s best enjoyed fresh from the fridge within a few days.
Wrapping Up
Keto Lemon Custard is proof that dessert can be light, bright, and low-carb without feeling like a compromise. With simple ingredients and a smart technique, you get a silky, citrusy spoon dessert that fits your goals. Make a batch for the week, or serve it at your next dinner—it’s an easy win either way.
Add berries, tweak the lemon, and make it your own. Enjoy the sunshine in every spoonful.
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