step 1
Melt butter in a pan and stir in the cookie crumbs. Press into the base of a 20cm springform cake tin. Chill until firm.
step 2
Whisk egg yolks in a bowl with the caster sugar until thickened. In a separate bowl beat the cheese until just softened and smooth. Whist into the egg yolk mixture then add the Bailey's and mix until smooth.
step 3
In a shallow dish, cover the gelatine with hot water. Leave to soak for a few minutes until softened, then drain and put into a pan with 2 Tablespoon water. Heat gently, swirling until dissolved. Cool then whisk into the cheese mixture, then fold in the zest. Whip double cream to soft peaks and fold in. Pour into the tin and chill at least 2 hours or overnight.
step 4
Melt chocolate then spoon into piping bag. Pipe stripes of chocolate over the cheesecake. Let set for a few minutes.