Using an electric mixer, beat the butter and sugar until pale and creamy. Add the egg and beat well. Mix almond meal and flour together, fold into the butter mix.
Place this pastry between 2 sheets of baking paper and, using a rolling pin, roll out to make a circle about 35cm in diameter. Chill until firm.
Take a tart tin 27cm in diameter and 3cm deep and line with pastry. Rest in the freezer for 20 minutes, until very firm.
Preheat oven to 170°C. Cover pastry with baking paper and fill with rice or beans, then bake for about 20 minutes, until the edges begin to colour. Remove weights and paper and continue to cook for a further 10 minutes, until the pastry is evenly browned. Allow to cool and trim off any pastry above the edge of the tart tin.
Increase oven to 180°C.
Whisk the 3 eggs, sugar, lemon and vanilla paste until combined. Add flour and whisk thoroughly.
Add butter to a small saucepan, melt over medium-high heat and continue cooking until nut brown. Gradually whisk the brown butter into the egg mix.
Put the blueberries into the tart case and pour over the egg mixture, filling it to just below the top of the pastry (there may be some left over). Bake for 40-50 minutes, until the filling is golden brown and just set. Remove from oven and allow to cool.
Combine caster sugar and 1 cup (250ml) water in a saucepan and bring to the boil. Remove from heat and add blueberries, allow to cool, then strain. Scatter the blueberries over the tart, drizzle with some of the syrup and serve with the whipped cream.