Preheat oven to 450 degrees F (230 degrees C). Arrange tart shells on a baking sheet.
Bake in the preheated oven for 6 minutes. Remove shells from oven and cool. Reduce oven temperature to 375 degrees F (190 degrees C).
Spoon 1 teaspoon raspberry jam into the bottom of each tart shell.
Beat butter and white sugar together in a bowl with an electric mixer until smooth and creamy. Add flour, egg, baking powder, and almond extract and mix well. Spoon 1 tablespoon butter mixture on top of raspberry jam layer.
Bake tarts in the preheated oven until filling is bubbling, 25 to 30 minutes.
Stir confectioners' sugar and water together in a bowl until icing is smooth; drizzle over warm tarts.