Keto Lemon Cake with Blackberry Mascarpone Frosting
Discover the ultimate low-carb indulgence with our Keto Lemon Cake with Blackberry Mascarpone Frosting. This moist delight boasts four layers of lemony goodness, filled with sugar-free lemon curd, and topped with a decadent blackberry frosting. It is perfect for springtime celebrations, and it's gluten-free too! Elevate your dessert game with this irresistible treat.
Equipment
Ingredients
For the Lemon Curd
- 1/2 cup unsalted butter
- 1 cup Besti Monk Fruit and Allulose Powdered Sweetener
- 3 large eggs + 1 egg yolk
- 1 cup freshly squeezed lemon juice
For the Lemon Cake
- 2/3 cup Wholesome Yum Coconut Flour
- 1/2 cup Oat Fiber
- 1/4 cup whey protein isolate unflavored
- 2 teaspoons gluten-free baking powder
- 1/2 teaspoon salt
- 1 cup unsalted butter softened
- 2/3 cup Besti Monk Fruit and Allulose crystalized sweetener
- 8 large eggs
- 1 cup heavy whipping cream
- 2 teaspoons vanilla extract
- 2 tablespoons lemon juice
- 2 tablespoons lemon zest
- 5-6 drops liquid sweetener to taste
For the Frosting
- 2 cups heavy whipping cream chilled
- 1 cup Besti Monk Fruit and Allulose Powdered Sweetener
- 2 cups mascarpone cheese chilled
- Zest from a large lemon
- 4-6 tablespoons sugar-free blackberry jam
For the Sugared Berries (optional)
- 1/4 cup water
- 1/2 cup Besti Monk fruit and Allulose Sweetener divided
- Fresh blackberries
Instructions
To make the Lemon Curd
- Melt the butter in a large microwave-safe bowl in the microwave for around 1 minute to 1 minute 30 seconds, or until fully melted.
- Whisk in the sweetener, and lemon juice, and whisk until smooth, then whisk in the eggs.
- Cook in the microwave on high in one-minute increments, whisking well after each minute until the mixture thickens enough that it coats the back of a spoon. The time may vary depending on your microwave's power.
- Once thickened, transfer into an airtight container or jar, pressing plastic wrap onto the curd to prevent a skin from forming. Refrigerate for at least 2 hours until set.
To make the Lemon Cake
- Preheat the oven to 350 F.
- Grease two 8-inch round cake pans with butter and line the pans with circles of parchment paper.
- In a large bowl, whisk together the coconut flour, oat fiber, protein isolate, baking powder, and salt; set aside.
- In a separate large bowl, use a hand mixer or stand mixer to whip the butter and granulated sweetener until well combined.
- Add the eggs one at a time, beating well after each addition. Stir in the heavy cream, vanilla extract, lemon juice, lemon zest, and liquid sweetener by hand.
- Add the dry ingredients and mix by hand until just incorporated.
- Divide the batter evenly between the prepared cake pans. Bake for 20 to 25 minutes, until a toothpick inserted in the middle of a cake, comes out clean.
- Let the layers rest for about 10 minutes before removing from the pans to cooling racks to cool completely.
To make the Frosting
- In a large mixing bowl, whip the heavy whipping cream with a hand mixer.
- As you whip the cream, add in the sweetener and extract.
- When thickened, add the mascarpone and blackberry jam and whip just until firm.
- Stir in the lemon zest by hand and refrigerate until ready to frost the cake. *See Notes
To assemble the Cake
- To assemble, slice each cake round in half horizontally.
- Place one layer on a cake plate or cardboard round and pipe a ring of the frosting around the edge.
- Spread 1/3 of the lemon curd on the layer inside of the ring of frosting. Use a light hand or a piping bag to cover the lemon curd with a layer of frosting.
- Add another layer of cake followed by piping another ring of frosting and adding another 1/3 of the lemon curd and another layer of frosting.
- Repeat until all four layers of cake are assembled.
- Cover the top and sides of the assembled cake with the remaining frosting.
- Cover and refrigerate for at least 8 hours or overnight before serving.
To make the Sugared Berries
- In a microwave-safe container, combine the water and 1/4 cup of sweetener. Stir together briefly.
- Microwave for 1 minute to create a simple syrup.
- Carefully remove from the microwave and stir in any remaining sweetener granules. Allow the simple syrup to cool for 5-10 minutes.
- Once the syrup has cooled, dip your berries into the syrup and then roll into the remaining sweetener.
- Set on a plate or pan and allow the syrup and sugar to dry and harden. This will take 5-10 minutes
- Once the berries have hardened decorate the top of the cake with the sugared berries.
Notes
If you refrigerate the frosting for longer than 30 minutes, the frosting may become too firm to work with easily.
Disclaimer
Most of my recipes are low-carb (or keto) and gluten-free, but some are not. Please verify that a recipe fits your needs before using it. Recommended and linked products are not guaranteed to be gluten-free. Recipes may contain errors, so please use your common sense when following them. Nutritional information is provided as a courtesy and is approximate only. We cannot guarantee the accuracy of the nutritional information given for any recipe on this site. Erythritol carbs will not be included as it has a glycemic index of 0 (meaning it does not spike blood sugar) and it’s not metabolized. Net carbs are the total carbs minus fiber.
Nutrition
Calories: 486kcalCarbohydrates: 9gProtein: 7gFat: 48gSaturated Fat: 30gPolyunsaturated Fat: 2gMonounsaturated Fat: 9gTrans Fat: 1gCholesterol: 158mgSodium: 275mgPotassium: 86mgFiber: 3gSugar: 4gVitamin A: 1632IUVitamin C: 8mgCalcium: 123mgIron: 0.4mg
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