For the Cake:

1. Preheat the oven to 350°F. Line a quarter-size rimmed baking sheet with parchment paper and spray the bottom and sides with nonstick cooking spray. Set aside.
2. In a stand mixer fitted with the paddle attachment, cream together the granulated sugar and softened butter at high speed until light and fluffy, about 5 minutes. Add the eggs one at a time on medium speed until completely incorporated, scraping the sides of the bowl as needed between additions.
3. In a medium bowl, sift together the einkorn flour and baking powder. Add the salt. In a separate small bowl, whisk together the milk, yogurt, and vanilla.
4. On low speed, add the flour mixture alternately with the milk mixture to the creamed butter and sugar, starting and ending with the flour. Mix just until completely incorporated, scraping the bowl after each addition.
5. Pour the batter into the prepared baking sheet. Bake for 18-20 minutes, until the cake springs back when gently pressed. Remove from the oven and set aside to cool completely.
6. Once cooled, cut the cake into 24 hearts using a 2-inch heart-shaped cookie cutter. Arrange on a half baking sheet in a single layer without overlapping, cover tightly with plastic wrap, and set aside until ready to decorate.

For the Chocolate Shell:

1. Place a silicone mold with 8 2.5-inch heart-shaped sections on a flat plate. 
2. Place one cup of chocolate candy coating wafers in a heatproof bowl. Melt completely in 10-second intervals in the microwave, stirring between each. If the melted candy/chocolate is too thick to spread easily, stir in 1/4 teaspoon of vegetable shortening. 
3. With a spoon, place about two teaspoons of melted chocolate coating in one of the heart-shaped molds. With a small brush or small spoon, spread to cover the inside of the mold. Repeat with the other seven sections. Transfer to the refrigerator to chill for 10 minutes, until completely hardened. 
4. Once hardened, remove from the refrigerator and apply a second coating of melted chocolate to each cavity in the mold, making sure to cover any missed holes or thin spots. If the chocolate coating is hardening, return to the microwave and heat in 10-second intervals, stirring between each, until melted. The shell should be about 1/8 inch thick. Transfer to the refrigerator to chill for another 10 minutes, until completely hardened. 
5. To remove the shells from the mold, carefully loosen all of the edges of one heart-shaped section. Starting from one end, carefully peel back the mold, holding the chocolate shell as you’re peeling, until the entire shell is removed. Repeat with the rest. 
6. Clean off any excess chocolate with your fingers or a small offset spatula. Transfer to a half sheet pan lined with parchment paper and place in the refrigerator until you are ready to decorate. 

To Decorate and Assemble:

1. To add sprinkles, drizzle any remaining melted chocolate coating on top of the exterior of each shell and quickly apply sprinkles before it sets. You may need to remelt the chocolate coating in 10-second intervals in the microwave.
2. Transfer to the refrigerator to chill for 10 minutes, until completely hardened.
3. When ready to assemble, lightly dust each piece of cake with powdered sugar. Place each cake on a small plate, and carefully place a chocolate shell on top. Serve, and enjoy!