Use this recipe when making our Chocolate and Raspberry Heart Napoleons.
Cut parchment paper to fit a 9-by-13-by-2-inch pan. Brush vegetable oil in corners and center of the pan, pressing parchment to adhere it. Set aside.
Bring a medium pot of water to a simmer. Place chocolate in a medium stainless-steel bowl; place the bowl over, but not in, the simmering water to melt the chocolate, about 4 to 6 minutes.
Remove chocolate from simmering water. Thoroughly dry bottom of bowl; a drop of water will ruin the chocolate. Pour chocolate into prepared pan. Using a large metal offset (bent-neck) spatula, spread the chocolate evenly over the surface 1/6 inch thick. Freeze until chocolate sets, about 6 minutes.
Working quickly, use a heart-shaped cookie cutter (3 1/4 inches across at widest point), to cut out 6 chocolate hearts. If chocolate begins to soften, return to freezer for several minutes. Run an offset spatula under the hearts, and place in a container. Cover and freeze until ready to use, up to 2 weeks.
Freezing these hearts eliminates the need to temper the chocolate.