Break up the chocolate

• Break the white chocolate into even-sized pieces so they all melt at the same time.

Coat the chocolate with cream

• Pour the double cream over the chocolate in a bowl.
• Stir with a spoon so all the chocolate is coated in the cream.

Microwave in two bursts

• Microwave for 1 minute, then push all the chocolate under the cream.
• Microwave for another 1 minute.

Stir until melted

• The chocolate will not be fully melted yet: stir with a spoon until it is completely melted and smooth.
• If large lumps remain, microwave for no more than 5 to 10 seconds at a time. Do not overheat or overmix, or the ganache will split and turn grainy.

Cover and leave overnight

• Lay cling film directly on the surface of the ganache.
• Leave it overnight to set until very thick.

Loosen and whisk

• Separate the portion needed for the crumb coat so crumbs do not get into the main batch.
• Microwave for 10 seconds to loosen, then whisk until smooth and spreadable.
• If the ganache thickens while using, microwave for a few seconds.