In a small bowl combine flour, baking powder, and salt; set aside. In a medium bowl beat sugar and shortening with an electric mixer on medium speed until fluffy. Add the egg, vanilla, and oil of cinnamon, if desired; beat well. Add flour mixture; beat well. Cover and chill in the refrigerator about 2 hours or until firm.
Cut a 10x8-inch heart pattern from paper. Halve dough. Line 2 cookie sheets with foil. Place half of the dough on each cookie sheet; roll into 10x8-inch rectangles. With pattern, cut dough into heart shapes. Reserve scraps. (If dough seems too soft, freeze 30 minutes or until firm.) Use alphabet- and heart-shaped cutters to cut out a message from each cookie. Remove dough from cutters.
Spoon candy into cutouts to fill holes to level of the dough. Bake in a 375 degree F oven for 10 to 12 minutes or until candy is melted and cookies are done. Cool on cookie sheets. Peel foil from cookies. Reroll dough scraps; cut with 3-inch cookie cutters. Place on ungreased cookie sheet. Bake in the 375 degree F oven for 10 to 12 minutes or until done. Cool on pan. Makes 2 large and 6 small cookies (18 servings).