In a food processor, combine the sugar, flour, salt, baking powder. When well combined, add the butter and pulse the machine until the butter is broken up into the flour mixture. Add the egg and water and process until the dough forms a dough.
Transfer the dough into waxed paper; pat it (with floured hands if need be) into a flat round and refrigerate for 30 to 45 minutes or until it has relaxed and you can roll it out.
Divide the dough into approximately 8 equal pieces. On a lightly floured board roll out the pieces until slightly thicker than 1/8th-inch thick. Rather than bother fitting them into tartlet shells and prebaking them, simply shape them into rough rounds (3 inches or 3 1/2 inches round) or cut them into hearts or rectangles. Transfer the free form shapes to a baking sheet and chill 20 minutes while you preheat the oven to 400 degrees. Scraps can be shaped into smaller cookies.
Prick the dough with a fork (just as you would the bottom dough of a tartlet shell) so the dough doesn't puff up. Bake for 10 to 12 minutes or until edges are brown. Remove them from the oven to a rack and let them cool. When completely cool top with whatever you like.
To make a topping that simulates a fruit tart gently warm the red currant jelly in a saucepan and brush over the free form tart shells. Arrange some sliced berries over the top and center a whole one in the middle if you wish. You can glaze with more warm currant glaze or pipe whipped cream on top or dust with confectioner's sugar.
You could also brush bottoms with warm glaze and set other fruit over top or brush bottoms with some lemon curd and top with fruit.