Whisk egg yolks and caster sugar together in a bowl.
Gently warm the milk with vanilla seeds and pods in a saucepan.
Heat the double cream in a separate pan.
Combine the warm milk and cream with the egg mixture.
Cook the mixture over gentle heat, stirring constantly until thickened.
Stir in crème fraîche, strain through a sieve, and discard vanilla pods.
Cool and churn the mixture in an ice cream machine until thick.
Transfer ice cream to a container and freeze.
Toast almonds in a pan, then chop them finely.
Mix almonds with flour, polenta, sugar, salt, and vanilla extract.
Rub in the chilled butter to form a crumble.
Spread crumble on a tray and chill for 30 minutes.
Preheat the oven to 140°C.
Bake the crumble for 40 minutes and allow it to cool.
Heat ginger wine, brown sugar, and orange zest until sugar dissolves.
Poach rhubarb in the liquid for 4 minutes until soft.
Drain cooled rhubarb and pack into 7.5cm rings to serve.
Top with crumble and a scoop of vanilla ice cream.