CRUST
1. Sift together flour, sugar, baking powder and salt in a bowl.
2. Cut in butter with a pastry blender or knife until the mixture resembles coarse breadcrumbs.
3. Add egg yolk and lemon juice. Blend in water, 1 tbsp at a time, until the dough can be formed into a ball.
4. Wrap in wax paper sprinkled with flour and chill for 30 minutes.
CASHEW FILLING
1. Spread strawberry jam and top with cashew nuts.
2. Preheat at 350°F / 175°C. Sprinkle flour onto a smooth work surface.
3. When crust has been chilled for 30 minutes, roll it out onto floured work surface using rolling pin, until it is 3mm (1/8-inch) thick.
4. Use a tart mold or knife to cut out the dough.
5. Combine and roll any remaining dough and cut out.
6. Brush tart molds with melted butter and place the cut out pieces of dough into each mold.
7. Pour about 1 tbsp of filling into each mold. Arrange tarts on a baking sheet and bake in the turbo broiler for 20 to 25 minutes at 350°F / 175°C or until pastry is light brown and filling is just firm (it will continue to firm up for a few minutes after it has been removed in turbo).
8. Remove from molds and wrap in cellophane if desired, or in an airtight container if not eating immediately.