Grease an 850ml pudding basin with butter and chill for five minutes.
Pour the maple syrup into the base of the chilled basin.
Mix the sponge ingredients, pour into the basin, and seal tightly with pleated buttered foil and string.
Steam the basin over boiling water for 90 minutes.
Heat the milk, cream, and vanilla pod in a saucepan.
Whisk egg yolks, caster sugar, and almond liqueur until light.
Whisk half the hot milk into the eggs, then return the entire mixture to the saucepan.
Cook over low heat while stirring until the custard thickens.
Boil blueberries, sugar, lemon juice, and 60ml of water, then simmer for five minutes.
Turn out the pudding and serve in wedges with the hot custard and compote.