"No oven, no bain-marie, no cracks—this is the simplest of cheesecakes! You can make this up to 2 days ahead, topping with honey and thyme just before serving if you like. It will keep in the fridge but the base will soften with time."
Line a 9-inch springform cake pan with parchment paper and set aside.
Line a sieve with a clean kitchen towel and set above a bowl. Spoon in the yogurt, then draw up the sides of the kitchen towel. Squeeze the yogurt into a ball, pressing out as much liquid as you can. You want to end up with about 1 2/3 cups of thickened yogurt. Set aside until required. Discard the liquid.
Place the Hobnobs in a clean plastic bag and crush them finely with a rolling pin. Mix with the butter and 1 tablespoon of the thyme and spoon into the cake pan, pressing it down to form an even layer. Set aside in the fridge.
Whisk together the cream cheese, strained yogurt, confectioners' sugar, and lemon zest until smooth and combined; this can be done in a stand mixer or using a handheld mixer.
Next melt the chocolate. This needs to be done in a heatproof bowl set over a pan of barely simmering water (taking care that the base of the bowl is not touching the water). Stir the chocolate frequently for 2 to 3 minutes, taking care not to get any moisture into the chocolate as this will cause it to seize. Spoon the melted chocolate into the cream cheese mixture and whisk until combined.
Spread the cream cheese mixture over the cookie base evenly, then refrigerate for at least 2 hours, until set.
When ready to serve, warm the honey in a small saucepan with the remaining 1 1/2 teaspoon of thyme leaves until thin and runny. Remove from the heat and drizzle over the cheesecake.
Release the cheesecake from the pan, divide into 8 slices, and serve.