1. Pastry: Combine plain flour, butter, icing sugar, and beaten egg in a mixing bowl or food processor. Process until the dough just comes together. Optionally, include almond flour for extra flavor and texture. Wrap pastry dough in cling wrap and chill in the fridge for at least 30 minutes.
2. Bring pastry to room temperature, then roll out on a lightly floured surface. Line 6 small tart tins (around 10cm diameter) or one 9-10 inch tart pan with pastry. Prick the base of each pastry case with a fork.
3. Chill the lined tins for 30 minutes. Meanwhile, preheat oven to 180°C (350°F) and place a heavy baking sheet inside to heat.
4. For blind baking, line pastry with crumpled baking paper and fill with baking beans or dried pulses. Place on heated baking sheet and bake for 10-20 minutes until lightly golden and set. Remove baking beans and paper, return to oven for a few minutes if needed, then set aside.
5. Frangipane Filling: Cream butter and sugar until soft and fluffy. Beat in egg(s), then fold in ground almonds, flour, almond extract, and salt. Mix briefly until smooth.
6. (Optional) For assembly layering: Spread a thin layer of raspberry preserves on the bottom of the tart shell and freeze briefly until firm. This helps prevent the preserves from mixing into the frangipane.
7. Spoon frangipane into each pastry case or tart shell, spreading evenly without disturbing the preserves if used.
8. Arrange fresh raspberries gently on top, spaced evenly (about ¼ inch apart). Sprinkle flaked or sliced almonds over the fruit.
9. Bake at 180°C (350°F) for 20-40 minutes for small tartlets, or 55-60 minutes for a large tart, until the frangipane is set and the crust is golden. If almonds brown too quickly, loosely cover the tart with foil to prevent burning.
10. Remove from oven and cool completely on a wire rack. Dust with powdered sugar before serving if desired. Serve at room temperature or chilled, optionally with cream or ice cream.