Keto Lemon Cupcakes with Raspberry Frosting

Introduction

Enjoy a perfect balance of bright, zesty lemon and sweet-tart raspberry without the carbs. These moist keto cupcakes are topped with a vibrant, creamy frosting that makes them a guilt-free indulgence for any occasion, from a simple treat to a special celebration.

Prep & Cook Time

Prep Time: 45 minutes

Cook Time: 35 minutes

Total Time: 1 hour 20 minutes

Servings: 12 cupcakes

Ingredients

For the Cupcakes:

• 2 tbsp butter
• 2 tbsp coconut oil
• 1/3 cup Joy Filled Eats Sweetener (or see alternatives in recipe notes) ()
• 2 eggs
• 3 egg whites ((save the yolks for the lemon curd))
• 1/4 cup sour cream
• 1 tsp lemon extract
• 1 oz lemon juice
• 1 tbsp lemon zest
• 2/3 cup almond flour
• 1/3 cup coconut flour
• 1 tsp baking powder
• 1/4 tsp salt

For the Lemon Curd Filling:

• 4 tbsp butter
• 1/4 cup Joy Filled Eats Sweetener (or see alternatives in recipe notes) ()
• 3 yolks
• 1.5 oz lemon juice

For the Raspberry Frosting:

• 6 tbsp butter
• 1/2 cup fresh or frozen raspberries
• 1 cup powdered sweetener ()
• 1 cup heavy cream

For Garnish:

• 12 fresh or frozen raspberries

Instructions

Make the Cupcakes:

1. Preheat your oven to 325°F (165°C). Line a 12-cup muffin tin with parchment or silicone liners.
2. In a microwave-safe bowl, melt the 2 tbsp butter and 2 tbsp coconut oil together. Transfer to a large mixing bowl.
3. Whisk the 1/3 cup sweetener into the melted fats until well combined.
4. Add the 2 whole eggs and 3 egg whites, sour cream, lemon extract, 1 oz lemon juice, and lemon zest to the bowl. Whisk vigorously until the mixture is smooth and fully emulsified.
5. In a separate bowl, whisk together the almond flour, coconut flour, baking powder, and salt.
6. Gently fold the dry ingredients into the wet ingredients until just combined and no dry streaks remain.
7. Divide the batter evenly among the 12 prepared muffin cups.
8. Bake for 30-35 minutes, or until the tops are golden and a toothpick inserted into the center comes out clean. Let the cupcakes cool in the pan for 5 minutes, then transfer them to a wire rack to cool completely.

Make the Lemon Curd Filling:

1. While the cupcakes cool, create a double boiler by placing a heatproof bowl over a saucepan of gently simmering water (ensure the bottom of the bowl does not touch the water).
2. In the bowl, combine the 4 tbsp butter, 1/4 cup sweetener, 3 yolks, and 1.5 oz lemon juice.
3. Whisk constantly for 8-12 minutes until the mixture thickens enough to coat the back of a spoon. It will continue to thicken as it cools.
4. Remove from heat, let cool slightly, then cover the surface directly with plastic wrap and refrigerate until cold and set.

Make the Raspberry Frosting:

1. In a small saucepan, melt the 6 tbsp butter with the 1/2 cup raspberries over medium-low heat. Cook for 5-7 minutes, mashing the berries, until the mixture is fragrant and the berries have broken down.
2. Strain the mixture through a fine-mesh sieve into a bowl, pressing with a spoon to extract all the liquid and color. Discard the seeds and pulp. Chill this raspberry butter in the refrigerator until solid (about 30-40 minutes).
3. Once solid, place the raspberry butter in a large mixing bowl. Add the 1 cup of powdered sweetener. Using a hand mixer or stand mixer, beat on high speed for 2-3 minutes until light and fluffy.
4. With the mixer running on low, slowly drizzle in the heavy cream. Once incorporated, increase the speed to high and whip for 2-4 minutes until the frosting is thick, stiff, and holds its shape.

Assemble the Cupcakes:

1. Once the cupcakes and lemon curd are completely cool, use a small knife or a cupcake corer to cut a small plug from the center of each cupcake.
2. Spoon or pipe the chilled lemon curd into the center of each cupcake, filling the hole.
3. Pipe or spread the raspberry frosting onto each cupcake.
4. Garnish each frosted cupcake with one of the 12 fresh or frozen raspberries.

Variations

• Lemon Glaze Instead of Frosting: For a simpler option, skip the frosting. Mix powdered sweetener with a little lemon juice and zest to create a thin glaze to drizzle over the cupcakes.
• Filling Swap: Use the raspberry frosting as a filling instead of the lemon curd for a pure raspberry experience, and top with a plain lemon cream cheese frosting.
• Mini Desserts: Bake the batter in a mini muffin tin for bite-sized treats, adjusting the bake time to 15-20 minutes.
• Layered Parfait: Crumble a cupcake into a glass, layer with lemon curd and a dollop of raspberry frosting, and repeat for a deconstructed dessert.

Tips for Success

• Ensure all ingredients, especially eggs, sour cream, and butter for the frosting, are at room temperature before making the cupcake batter for the best texture.
• When making the lemon curd, whisk constantly and keep the heat low to prevent the eggs from scrambling.
• Chill the raspberry butter until completely solid. If it’s too soft, the frosting won’t whip up properly and may be runny.
• For the smoothest, seedless raspberry frosting, be patient when straining the berry mixture and press firmly to get all the flavorful juice.

Storage & Reheating

Store assembled cupcakes in an airtight container in the refrigerator for up to 4 days. For best texture, let them sit at room temperature for 15-20 minutes before serving. The cupcakes can be frozen (unfrosted) for up to 2 months; thaw overnight in the fridge before filling and frosting.

FAQ

Can I use a different sweetener?

Yes, but use a granulated, keto-friendly sweetener that measures 1:1 like erythritol or monk fruit blend for the cupcakes and curd. For the frosting, a powdered version of the same sweetener is essential.

My frosting is too soft. What happened?

This is usually because the raspberry butter wasn’t chilled enough, the heavy cream was too warm, or the kitchen was very warm. Place the whole bowl of frosting in the refrigerator for 20 minutes, then whip it again.

Can I make this nut-free?

No, this recipe specifically uses almond flour. Substituting it would require a complete reformulation of the dry ingredients and is not recommended.

What can I do with the leftover egg whites from the curd?

You can use them in other keto recipes like egg white “crepes,” meringues (using a keto sweetener), or add them to a scramble for extra protein.

Do I have to fill the cupcakes?

No, the filling is optional. You can simply bake, cool, and frost them for a delicious, slightly simpler cupcake.

Can I use store-bought lemon curd?

If you can find a sugar-free, keto-friendly lemon curd, you can use it to save time. Be sure to check the carb count.