Preheat oven to 160C. Grease and line a 18x28m tray with baking paper.
Melt chocolate and butter together in a heat proof bowl over simmering water. Allow to cool slightly.
Whisk together the eggs and vanilla, add the cooled chocolate mixture, flour and sugar. Mix until just combined. Press into prepared tray
Beat the cream cheese and extra sugar until creamy and smooth. Add egg and strawberry essence and mix well. Tint with food colour and swirl until desired colour achieved.
Spread evenly over the base, and then swirl the base layer and cheesecake layer together with a knife or kitchen skewer.
Bake for 35-40 minutes, until crumbs cling to a skewer inserted in the centre. Allow to cool fully before slicing.