First of all, make and chill the pastry, then line a 28cm loose-bottomed tart tin with it. Place in the freezer for 1 hour.
Preheat the oven to 180°C/350°F/gas 4, then take the pastry case out of the freezer and bake for 15 minutes, or until lightly golden. Remove from the oven and allow to cool slightly.
Turn the oven down to 170°C/325°F/gas 3.
To make the frangipane, blitz the whole almonds in a food processor until you have a fine powder and put this into a bowl. Beat the butter and sugar together until light and creamy, then add to the almonds.
Lightly beat the eggs and add to the mixture. Fold in until completely mixed and smooth, then place in the fridge to firm up slightly.
Spread the jam over the pastry case. Pour the chilled frangipane mixture on top, and sprinkle with some flaked almonds.
Bake the tart for 40 minutes, or until the almond mixture has become firm and golden on the outside but is still soft in the middle.
Allow to cool for about 30 minutes, then serve with crème fraîche or yoghurt.