Keto Boston Cream Pie Bars

Boston cream pie has always been one of my favorite bakery treats, but the traditional version is loaded with sugar.

That is why I created these keto boston cream pie bars, so you can enjoy all the classic flavors without going off track.

This dessert is completely low carb and keto friendly, which means you can satisfy your sweet tooth without spiking your blood sugar.

You get a soft vanilla cake base, a rich custard layer in the middle, and a smooth chocolate glaze right on top.

They are surprisingly easy to make and slice into neat little squares that anyone can enjoy.

Why You’ll Love This Recipe

Authentic Bakery Layers – You get three distinct layers of moist cake, velvety custard, and glossy ganache in every single bite.

True Classic Flavor – It tastes just like real Boston cream pie while keeping your carbs exceptionally low.

Incredibly Tender Sponge – Adding sour cream ensures the almond flour vanilla cake stays perfectly soft, rich, and moist.

Perfectly Stable Custard – The foolproof gelatin custard sets firmly so the bars slice cleanly without making any mess.

Recipe Ingredients

For the Vanilla Cake

• 1 1/2 cups Almond Flour
• 2 tbsp Coconut Flour
• 1/2 cup Granulated Erythritol
• 1 1/2 tsp Baking Powder
• 1/4 tsp Salt
• 3 large Eggs
• 1/4 cup Butter, Melted
• 1/4 cup Sour Cream
• 1/4 cup Unsweetened Almond Milk
• 2 tsp Vanilla Extract

For the Custard

• 1 1/2 tsp Unflavored Gelatin
• 1 tbsp Cold Water
• 1 cup Heavy Cream
• 1/2 cup Unsweetened Almond Milk
• 3 large Egg Yolks
• 1/4 cup Powdered Erythritol
• 1/4 tsp Xanthan Gum
• 1 tbsp Butter
• 1 1/2 tsp Vanilla Extract

For the Ganache

• 2/3 cup Sugar Free Dark Chocolate Chips
• 1/3 cup Heavy Cream
• 1 tbsp Butter

How To Make

Step 1

Preheat the oven to 350°F and line an 8×8-inch baking pan with parchment paper, leaving overhang on two sides.

Step 2

Whisk together the almond flour, coconut flour, granulated erythritol, baking powder and salt. In another bowl whisk the eggs, melted butter, sour cream, almond milk and vanilla, then combine the two into a smooth, thick batter.

Step 3

Spread the batter in the pan and bake for 20 to 24 minutes, until golden and a toothpick comes out clean. Cool completely in the pan.

Step 4

Sprinkle the gelatin over the cold water to bloom. Whisk the xanthan gum into the powdered erythritol, then whisk this with the egg yolks until pale.

Step 5

Heat the heavy cream and almond milk until steaming and slowly whisk it into the yolks. Return to the saucepan and cook over medium-low heat, stirring constantly, for 4 to 5 minutes until thickened.

Off the heat, stir in the gelatin, butter and vanilla. Let cool for 15 minutes, stirring occasionally.

Step 6

Pour the custard over the cooled cake and chill for 1 1/2 hours, until set.

Step 7

Heat 1/3 cup heavy cream until steaming and pour it over the chocolate chips and butter. Let sit for 2 minutes, stir until glossy, then cool for 10 minutes.

Step 8

Spread the ganache over the custard and chill for 30 minutes. Lift out and slice into 16 bars.

Tips

Blend the Xanthan Gum into the Sweetener First

Xanthan gum binds with liquid almost instantly and forms gummy clumps if you drop it straight in. Whisking it thoroughly into the dry powdered erythritol first solves this problem completely.

From my experience, this separates the gum particles so they dissolve evenly into the egg yolks. You will end up with a silky smooth custard without any chewy lumps.

Pour the Hot Cream Slowly into the Yolks

If you add the hot cream mixture into the egg yolks all at once, the heat will cook the eggs into tiny solid pieces.

You will get the best results if you pour just a tiny stream of the hot liquid in while whisking as fast as you can.

Once the yolks are warm and adjusted to the temperature, you can safely pour everything back into the pot to finish cooking.

Always Use Powdered Sweetener for the Custard

Granulated erythritol does not stay melted once it goes into the fridge. If you use it in the custard, the crystals will firm back up and make the filling feel gritty.

I recommend using a finely powdered sweetener so the custard stays smooth and creamy even after hours in the refrigerator. If you only have granulated sweetener, you can pulse it in a clean coffee grinder or blender until it becomes a fine powder.

More Recipes

• Keto Boston Cream Pie Cupcakes
• Keto Coconut Cream Pie
• Keto Cream Puffs
• Keto Millionaire Shortbread Bars
• Keto Tiramisu Brownie Bars

Frequently Asked Questions

Can I use granulated sweetener instead of powdered for the custard?

It is best to stick with powdered erythritol because granulated sweetener will not dissolve well in the custard.

If you use granulated erythritol, your custard layer will likely end up gritty and could crystallize once chilled.