• Cold-process soapmaking is chemistry, and this recipe uses lye. Lye is a caustic substance that is completely neutralized in the soapmaking process, but it can be harmful if not handled correctly. Please read this soap making safety guidance before proceeding.

Mixing the Mica

• In a small container, mix the powdered gold mica powder into two teaspoons of olive oil. A small fork, mini whisk, or milk frother will help to blend it into what looks like liquid gold! Use the olive oil called for in the recipe rather than adding more.

Make the Lye Solution

• Put on your rubber gloves and eye protection (goggles) and set yourself up in an area with good ventilation. Under a hob, on the doorstep, or outdoors is perfect. Pour the sodium hydroxide into the water and stir with a stainless steel spoon. Be careful not to breathe in the fumes. Stir until the lye is completely dissolved.
• Set the jug aside to cool to 120°F / 49°C. To help speed up cooling, place the steaming jug of lye solution in cool water. I tend to place jugs of lye solution in the sink and fill it with water up to the level of the lye solution in the jug.

Melt the Solid Oils

• While the lye solution is cooling, begin melting the solid oils together on the lowest heat possible on your hob. When there are just a few pieces of solid oil floating in the pan, turn off the heat and move the pan to a potholder. Stir with your spatula until all of the oils are melted.

Add the Liquid Oils

• When the solid oils are melted, pour the liquid oils into the pan. Use the spatula to get as much of it in as possible (castor oil has a real tendency to stick). Now measure the temperature of your oils with your digital thermometer. You're also aiming to get it down to about 120°F / 49°C or slightly higher.

Balance the Temperatures

• Once you have a read on your oil temperature, head back over to the lye solution and take its temperature too. It's fine to go back and forth with the digital thermometer for both. The lye solution should be within ten degrees of the oils and can be either warmer or cooler.

Immersion Blending

• When the temperatures are right, it's time to mix the lye solution with the oils. Pour the lye solution through a mini strainer (to catch any pieces that might not have dissolved) and into the pan of warm oils.
• Next, place the immersion blender into the pan and use it to stir the mixture together gently. The head of the immersion blender should be completely immersed in the oil-lye solution.
• Bring the immersion blender to a stand-still in the center of your pan and then press pulse for a few seconds. Then stir gently again for a moment and repeat the stand-still blending.
• Continue pulsing and stirring your soap batter until it hits a light trace. This means that the batter thickens and if some of it dribbles down from the immersion blender, it will leave a mark on the surface of your soap batter before melting back in. It's important for this recipe that the trace is not too thick, otherwise, it will be difficult to create the effect.

Add the honey

• When your soap batter has thickened to a light trace, stir in the honey. Give it a good 20-30 seconds of stirring.
• If you wanted to add any optional essential oil (or fragrance oil) to the soap, you can do it now.

Divide the soap batter

• Pour about a third of the soap batter into a separate container (a small plastic jug or bowl will do) and then pour the gold mica oil into it. Stir well.

Layering the soap batter in the mold

• Now the fun part! To get the same effect you'll need the same 6 Cavity silicone soap mold that I'm using. You can adapt the technique for a larger loaf mold but it will turn out looking a bit different.
• Alternate pouring a Tablespoon of the uncolored soap batter into one corner of each cavity, with pouring a teaspoon of the gold soap batter directly on top. A Tablespoon of the white batter, a teaspoon of the gold in the same exact spot until it's filled.

  I filled all six cavities at the same time instead of focusing on just one. It might speed up the process.

Decorate the tops of the Christmas soap

• To finish the soap, I used a chopstick to lightly swirl the tops of the bars and then dust them with gold mica. Use a fine sieve to dust the soap just as you'd dust a dessert with icing sugar.
• You're finished for now. Leave the soap on a kitchen worktop, or another place that's room temperature or slightly warmer, and leave it for 48 hours.

Curing the Christmas soap

• After the time has passed you can pop the Christmas soap out of the mold. It's relatively soft, to begin with, but as it cures, it will harden. Doesn't it look delicious too? I'd recommend against using a fudge scented fragrance oil for this recipe because you don't want to cause any confusion!
• Next is the hard part -- waiting for your soap to cure. Keep your bars in a cool, dry, airy, and dim place for four to six weeks. Place them on a bookshelf on a layer of greaseproof or baking paper. Ensure that each bar has plenty of airflow around it. During the cure time, the excess water will evaporate from your bars and the soap's crystalline structure will develop. It's important to wait the full time if you want your soap to function and feel good on the skin.
• After curing, your soap is ready to be used. For the holidays, wrap the soaps in festive paper and string -- I recommend red and white bakers twine.
• Once made, your Christmas soap will have a shelf-life of up to two years. Check the oil bottles that you're using though -- the closest best-by date is the best-by date of your soap. That's because some of that oil is free-floating in your bars as the superfat, and it can go rancid over time.