First, make the shortbread base. Heat
oven to 160C/140C fan/gas 3. Rub the
butter into the flour and sugar until the
mixture makes a sticky dough. You can
do this by hand or in a food processor.
Press evenly into the base of a non-stick
26cm springform tin and smooth with the
back of a metal spoon. Prick all over with
a fork, then bake for 25-30 mins until pale
golden. Cool, then carefully oil the sides
of the tin using kitchen paper.
To make the filling, soak the gelatine
in cold water for a few mins to soften.
Meanwhile, purée the strawberries in a
food processor or with a hand blender
until very smooth, then rub through a
sieve to remove all the seeds. Pour the
milk into a small pan and warm gently.
Squeeze the gelatine of excess water,
add to the milk, then remove from the
heat and stir to dissolve. Cool.
Stir the strawberry purée, gelatine
mixture, ricotta and sugar together until
smooth. In a separate bowl, whisk the
cream until it softly holds its shape, then
fold into the strawberry mixture with
three-quarters of the marshmallows.
Carefully pour onto the cooled base and
scatter over the remaining marshmallows.
Cover the tin with cling film and chill until
firm, preferably overnight. Cheesecake
can be made 2 days ahead if kept chilled.
Carefully remove the cheesecake from
the tin. Decorate with extra berries and
finish with a dusting of icing sugar.