Lightly grease your baking pan to ensure easy removal of the cake later. Cut a piece of parchment paper to fit the bottom of the pan and place it inside.

Break the tea biscuits into bite-sized pieces, approximately 1-2 cm in size. Be careful not to crush them into crumbs; the pieces should remain chunky to provide texture.

Melt the chocolate either in the microwave in short intervals or over a simmering bowl of water. Stir occasionally until fully melted and smooth.

While the chocolate is melting, whip the softened butter and sugar together until light and fluffy. If using dairy-free butter, it’s okay if the butter doesn't become very fluffy. You can melt or partially soften it and then mix in the sugar.

Once the chocolate is fully melted, pour it into the butter and sugar mixture. Stir thoroughly until well combined. Add in the water, then fold in the broken biscuit pieces, making sure each piece is coated with the chocolate mixture.

Pour the mixture into the prepared cake pan. Use a spatula to lightly but firmly press it into the pan, ensuring an even layer.

Place the cake in the refrigerator and let it chill until the chocolate is firm, about 30 minutes.

In a saucepan, combine the dairy-free whipping cream and chopped chocolate. Place the pan over medium-low heat and gently simmer, stirring frequently, until the chocolate has melted and the mixture is smooth.

Once the ganache is smooth and fully melted, remove the saucepan from the heat. Turn off the stove and prepare to assemble the cake.

Remove the chilled cake from the refrigerator. Place it on a wire rack set over a tray to catch any excess ganache that drips off.

Pour the ganache over the top of the cake, allowing it to flow over the sides. Use a knife or spatula to smooth the top and sides of the cake, ensuring an even coating.

Allow the ganache to set for a few minutes before decorating.

Decorate the cake as desired. You can add whole or broken tea biscuits, shaved chocolate, or a drizzle of any remaining ganache for an elegant finish.