Sift the flour, baking powder, and salt together in a bowl; set aside.
Beat the 1 cup butter with the sugar, egg, milk, and vanilla extract in another bowl until well mixed.
Gradually mix the flour mixture into the butter mixture.
Shape the dough into a disk; wrap with plastic wrap and refrigerate for at least 2 hours.
Working with half the dough at a time, roll out dough to about 1/8-inch thick.
Cut into cookies with a large heart shaped cookie cutter. Repeat with the remaining half of the dough.
Cut the center of half of the cookies with a smaller heart shaped cookie cutter.
Place an open centered cookie on top of a whole cookie to form a sandwich. Arrange cookies on an ungreased baking sheet; set aside.
Preheat an oven to 400 degrees F (200 degrees C).
Place the raspberry jam in a microwave save bowl and heat on high until jam is runny, about 35 seconds.
Fill the center of the cookies with the jam. Refrigerate cookies for 10 minutes.
Bake in the preheated oven until the cookies are firm to the touch, 5 to 8 minutes. Cookies will be pale in color.
Transfer cookies to a wire rack to cool completely.
Melt the chocolate and 2 tablespoons butter in a microwave-safe glass or ceramic bowl in 30-second intervals, stirring after each melting until smooth, for 1 to 3 minutes, depending on your microwave.
Spoon chocolate decoratively over half of each cookie.
Place cookie on a waxed paper lined baking sheet and refrigerate until the chocolate has set, about 15 minutes.