Preheat oven to 210°C. Grease base and side of a 23cm springform cake pan and line with baking paper. Grease a baking tray and line with baking paper.
To make the base, place biscuits in a food processor and whiz to fine crumbs. Transfer to a bowl with butter and almonds, and stir until well combined. Press mixture into the base of the prepared pan and smooth with the back of a spoon. Chill until needed.
To make the apricot layer, spread half the apricot, cut-side up, across the prepared tray and roast for 25 minutes or until apricot is soft but still holding its shape. Set aside to cool. Reduce oven to 170°C.
For the filling, place cream cheese, sugar, vanilla seeds and orange zest in a stand mixer fitted with the paddle attachment and beat until smooth. Add eggs, 1 at a time, beating well after each addition, then add sour cream and beat until combined. Stir through almond extract.
Arrange cooled roasted apricot, cut-side down, evenly across cheesecake base, without overlapping or leaving gaps. Gently pour filling over apricot layer, then place on a baking tray. Bake for 1 hour or until the edges are set but the middle has a slight wobble when shaken gently. Turn off oven and cool with the door ajar for 1 hour, then chill for at least 3 hours or overnight to set. (Cheesecake can be stored, chilled, for up to 3 days).
When ready to serve, preheat oven to 210°C. Grease a baking tray and line with baking paper. Spread the remaining fruit, cut-side up, across prepared tray and roast for 25 minutes or until apricot is soft but still holding its shape. Sprinkle apricots with caster sugar, almond extract and 1 tbs water, and bake for 10 minutes or until apricot is moist and syrupy. Remove from oven and set aside to cool.
Remove cold cheesecake from pan and transfer to a platter. Dust with icing sugar. Spoon the cooled apricot mixture onto the centre of the cheesecake. Sprinkle with extra almonds to serve.