When you can’t decide on a Boston Cream Pie or Chocolate Mousse Cake
you make both!
Boston Mousse Cake will become your new go to recipe for every occasion!
Layers of vanilla cake and chocolate cake with vanilla custard and chocolate mousse filling!
All the elements of the Boston Cream Pie and the Chocolate Mousse cake
Joined together in delicious matrimony with ganche icing draped over the entire cake
I’ve been lightening up my baking since the start of 2023 by using sugar alternatives in many of my bakes
The great news is you can implement those healthier choices in every recipe I am making today!
From both cake recipes to both fillings and even a ganache icing can all be made sugar free!
CLICK HERE FOR MORE ABOUT SUGAR FREE BAKING!
Notes for Success:
Cornstarch is a very difficult ingredient to measure consistently with a volume/spoons measure
So while I list both measures below I cannot stress enough how the grams measure with a scale is going to give you the best results.
Many times people have complained that their custard is like rubber and they don’t know why!
In the video you will see I used agar powder but it is not necessary in the chocolate mousse as it will set fine without it
In the video I ended up making a 4 layer cake but my intention was to make a 5 layer cake.
The recipes below are listed for a 5 layer cake for 3-7″ Vanilla Cake Layers and 2- 7″ chocolate layers
So if you only want to make four layers, simply wrap that extra layer and keep it int he freezer for another project!
WATCH HOW TO MAKE THE BOSTON MOUSSE CAKE
Boston Mousse Cake
Ingredients
For the Custard:
- 2¼ cup Plant Milk 533ml
- ¾ cup Granulated Sugar 150g
- 5 Tbs Cornstarch 40g
- ¼ teaspoon Turmeric
- 1½ Tbs Vegan Butter 21g
- 1 teaspoon Vanilla Extract 5ml
For the Chocolate Mousse:
- 8 ounces Semi Sweet Vegan Chocolate 226g
- 2 Tbs Hot brewed coffee 30ml
- 1 teaspoon Vanilla Extract 5ml
- ¼ cup Aquafaba 60ml
- 4 Tbs Granulated Sugar 50g
- ¼ teaspoon Cream Of Tartar
- 1½ cups Vegan Whipped Cream
for the icing
- 2 Recipe Ganache
- 1 Recipe Chocolate Buttercream
Instructions
- First prepare the chocolate cake recipe as per the instructions on that recipe post & divide the batter into 2-7" cake pans that have been greased & parchment lined.
- Bake in a preheated 350°F oven for approximately 20 minutes or when they are springy to the touch when you gently press the centers
- Cool the cakes in the pans then flip them out onto a cooling rack to cool the rest of the way.
- Wash & re-grease & re-parchment line the pans, but this time you need 3-7" cake pans
- Prepare the yellow cake recipe as per the instructions on that recipe post & divide the batter evenly between your prepared pans
- Bake in a preheated 350°F oven for approximately 20 minutes or when they are springy to the touch when you gently press the centers
- Cool the cakes in the pans and then flip them out onto a cooling rack to cool the rest of the way.
- Next prepare the chocolate buttercream according to the instructions on that recipe post
- Next prepare the custard: combine all the ingredients except for the vanilla extract& the vegan butter in a medium sauce pot over & cook over medium to high heat bringing to a boil stirring constantly to avoid scorching the bottom .
- Once it starts to bubble let it boil on low heat for about 5 seconds.
- Remove from the heat & add the vegan butter & vanilla extract stir until melted & smooth, reserve aside while you prepare the chocolate mousse recipe
- For the chocolate mousse Melt the chocolate in a large bowl over a double boiler or in a microwave safe bowl
- Combine the hot coffee & sugar in a small sauce pot and bring it to a rolling boil to dissolve the sugar
- Next prepare your favorite vegan whipped cream *You will need 1½ cups total fully whipped cream
- Add the hot brewed coffee & then the vanilla extract to the melted chocolate all at once while whisking vigorously to incorporate well.
- Cool the chocolate mixture to about 80°F or tepid to the touch before folding in the whipped cream or it will melt back to liquid!
- Add the reserved whipped cream & whisk smooth
- Whip the aquafaba with the cream of tartar to stiff glossy peaks
- Take a small portion of the AF meringue & fold into the chocolate mixture to lighten. Then fold in the rest of the AF gently
- Set up your first cake layer in a cake ring mold lined with acetate cake strips *see video tutorial
- Then build the cake inside the ring mold with a chocolate buttercream border to hold everything in alternating the cake layers as shown in the video tutorial
Video
Notes
Do you have a cookbook? I was looking and can’t seem to find one – ads drive me nuts. I know they’re integral to a blog but it’s so frustrating so I go for books when possible 🙂
Love your recipes. They’re so creative.
Hi Caitlyn thank you! Yes it’s true ads are really annoying unfortunately it is the only way I get paid (although it’s literally in pennies…..)
I recently implemented the “jump to recipe” button for a better user experience.
Yes I have a cookbook~ thank you for asking. CLICK HERE
also sold at Barnes & Noble
oh my gosh I just couldn’t find it- thank you!!! so excited
Hi Gretchen!
I love your cake recipes. I baked your hazelnut cake for my birthday and it was a hit! I am looking forward to preparing this cake tomorrow, but I have a couple questions. Can I prepare the mousse and custard a day in advance? and assemble all elements of this cake chilled?
Thank you so much!!
Olivia :))
Excellent! I’m happy it turned out well for you!
I think I mentioned in the video tutorial for this cake? that I prefer to build everything on one day this way the mousse & the custard set INSIDE the cake giving it much more stability for each slice rather than scoop & spread an already set custard which breaks the cornstarch bond & runs the risk of a loose runny custard~ although it can certainly be done this way! I think I just like the look of a very clean slice (*especially for photo taking for my website!)
The mousse though is much more forgiving and can be done either way since it stays pretty firm