Pour your measured double cream into a microwave safe bowl and heat in 30 sec. intervals until hot. Go slow and steady as it shouldn't boil. Once hot, break white chocolate into pieces and add it to the cream. Let it sit for couple of minutes until the chocolate melts. Add in the rest of the ingredients and use immersion blender to carefully blend everything together. Pour into storage container and cover to touch with cling film. Store in the fridge until set, preferably overnight or at least 6 hours.
Macarons
Start with measuring your almond flour and icing sugar. Make sure you sift them into your mixing wold to prevent any larger pieces of almonds getting into your batter as they would cause lumpy macarons. Measure your almond flour once you sift it. Add sifted sugar, mix properly and set aside.
Measure your egg whites into heat proof bowl, add in white sugar and place on the top of small pot with some simmering hot water. The bowl should not touch the water. Keep mixing gently with a whisk until all the sugar melted. Once all the sugar crystals have melted, take the bowl off the heat and start whisking the egg whites with electric whisk on medium speed until you get glossy stiff peaks. Once you have whipped your meringue, add the almond flour and sugar and start folding the mixture slowly. When you have most of the ingredients combined, add your food colouring. Keep folding/macaronaging until you have smooth batter that is thick but still holds its shape little bit, it should not be runny.
Transfer your macaron batter into a piping bag with round tip and pipe macarons on your baking at/making paper. Once the tray is full, give it a little bang with your hand to resolve nay air bubbles. No need to overdo it, just couple times is fine. You can use paper macaron size sheet underneath the mat to make sure they're all the same size. Let them sit for about 15-20 mins fr the shells to dry out. You can pre-heat the oven in the meantime to 135º-150ºC. Once your macarons are dry to touch, put them in the oven and bake for about 12-17 mins. Take them out of the oven and et them cool completely before removing from the mat, they could break if they're still hot.
Assembling
Transfer your ganache into a piping bag with a round tip. Take one macaron shell and pipe some of the ganache, cover with second shell and continue until you fill all the shells. Place them into an airtight container and store in the fridge, they should rest overnight to mature.