We’re doing a bit of calorie-free “baking” today with some downright delicious Chocolate Ganache Fizzing Bath Biscuits! These fun, fizzy bath treats were inspired by a request from Bethany + some LUSH products I’ve been ogling for a while. When I first started work on these I didn’t think I’d end up with some delicious bath cookies, but I love how they’ve turned out! They’re like the lovechild of a bubbly bath bomb and bath oil, filling your tub with bubbles and suds and transforming the bathwater into a rich, velvety treat. Oooer. Prepare to fall in love!

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I had so much fun with this DIY—playing with different ratios for the core ingredients, experimenting with different end consistencies, taking lots of baths to test performance, and devising a novel way to present them. Earlier versions of these bath biscuits were both far too liquidy (resulting in a thing I could pour into a mould nicely, but there was too low of a concentration of the powdery things to do much in the tub) and too firm (like stiff mashed potatoes, making nice presentation hard). After a few less-than-awesome variations I took a look at some similar projects from Brambleberry to get a bit of an idea of which direction to head in. My key takeaways were the inclusion of some liquid oil and the incorporation of a post-making drying/hardening/setting-up time, and those things really helped!

The bulk of this DIY is a blend of basic baking soda and acidic Cream of Tartar + citric acid—much like a bath bomb, really. That’s what gives these little bath biscuits their fizz! When they mix with water the acidic and basic ingredients collide, releasing carbon dioxide in a very fun way.

Some Sodium Lauryl Sulfoacetate (SLSa) contributes some gorgeous, creamy lather as these beauties break down and fizz away as your bath water runs. It also helps all the lovely cocoa butter in the formula blend with your bath water and wash down the drain, reducing the slippiness that can happen in a bath where there’s been quite a lot of oil in the bathwater.

All the powdery ingredients create a soft, rich dough when mixed with the melted cocoa butter, and we’ll take that soft dough and form it into some little thumbprint-style cookies. A brown mica drizzle channels a chocolate drizzle, and some bursting beads and popping cocoa butter bits from Brambleberry’s new Dreamy Desserts collection look a whole lot like sprinkles 🤤 The fragrance I chose is also from their new collection—the utterly mouthwatering Chocolate Ganache fragrance oil. You could easily use something else dessert-y; we already get some good cocoa-y notes from the cocoa butter, so something like vanilla-like benzoin resinoid or sweet orange essential oil would also be lovely!

Once we leave the bath biscuits to harden for a day or two, they’re ready to enjoy! Simply crumble one or two into running bath water and enjoy the fizzing, bubbles, and gloriously velvety bathwater. You might also want to make sure you’ve got some chocolate on hand… I edited out an embarrassing number of muttered “oh man, I want cookies!” type remarks from the video 😂 These beauties will have you craving desserts like mad!

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Chocolate Ganache Fizzing Bath Biscuits

Heated phase
15g | 15% cocoa butter
4g | 4% liquid oil (jojoba oil (USA / Canada), apricot kernel oil (USA / Canada), safflower oil, etc.)
40g | 40% baking soda
10g | 10% citric acid
10g | 10% Cream of Tartar
20g | 20% Sodium Lauryl Sulfoacetate (SLSa) (USA / Canada)
0.2g | 0.2% chocolate-y mica

Cool down phase
0.8g | 0.8% Chocolate Ganache fragrance oil

To decorate (all as needed)
White bursting beads
Cocoa butter popping crystals
Chocolate-y mica, pre-dispersed in 99% isopropyl alcohol

Prepare a water bath by bringing about 3cm/1″ of water to a bare simmer over low to medium-low heat in a small saucepan.

Weigh the heated phase ingredients into a small heat-resistant glass measuring cup or bowl. Place the measuring cup in your prepared water bath to melt everything through.

After about 20–30 minutes the cocoa butter should be completely melted. Remove the measuring cup from the heat and start stirring and mashing the mixture with a spoon—mix until uniform.

Weigh in the cool down phase and stir to incorporate. When the dough has cooled enough to handle it should have a soft play-dough type consistency. Form it into balls; I divided a 100g (3.5oz) batch into six balls, each approximately walnut-sized. Use a finger or thumb to press a small indentation into the top of each ball. Sprinkle with the bursting beads and popping crystals, and then drizzle with the mica/alcohol mixture. Leave to harden for a day before using.

To use, crumble one or two bath cookies into a running bath and enjoy!

Because these bath biscuits are 100% oil based, they do not require a broad-spectrum preservative (broad spectrum preservatives ward off microbial growth, and microbes require water to live—no water, no microbes!). Kept reasonably cool and dry, they should last at least a year before any of the oils go rancid. If you notice they start to smell like old nuts or crayons, that’s a sign that the oils have begun to oxidize; chuck them out and make a fresh batch if that happens.

Substitutions

As always, be aware that making substitutions will change the final product. While these swaps won’t break the recipe, you will get a different final product than I did.

• As I’ve provided this recipe in percentages as well as grams you can easily calculate it to any size using a simple spreadsheet as I’ve explained in this post. As written in grams this recipe will make 100g, which makes 6 walnut-sized bath biscuits.
• To learn more about the ingredients used in this recipe, including why they’re included and what you can substitute them with, please visit the Humblebee & Me Encyclopedia. It doesn’t have everything in it yet, but there’s lots of good information there! If I have not given a specific substitution suggestion in this list please look up the ingredient in the encyclopedia before asking.
• You could use refined cocoa butter instead of unrefined, but I do recommend unrefined.
• You can use any light-to-mid-weight, inexpensive liquid oil. Sweet almond, grapeseed, or sunflower seed would all be good choices (in addition to the ones listed above).
• Do not substitute the baking soda.
• You can try using all of either citric acid or Cream of Tartar.
• You could try a different powdered surfactant instead of Sodium Lauryl Sulfoacetate (SLSa).
• You could scent and/or decorate them differently if you like.
• You could use normal baking sprinkles instead of the bursting beads/cocoa crystals.
• You could use isododecane or cyclomethicone instead of isopropyl alcohol.