Ganache: Place the chocolate in a small bowl, bring the cream to a low boil and pour over the chocolate. Let sit about 3 minutes then stir until smooth, melted and glossy. Immediately pour through a sieve into another bowl to remove any small, un-melted bits-they will probably melt as you strain it. Leave the ganache in the bowl until ready to spread on the cake - do not stir! The ganache needs to cool from 3 to 5 hours, until spreadable*.
Cake: Set a rack in the center of the oven and preheat to 350 F. Butter and flour a springform pan. Sift together the flour, cocoa powder, baking powder, baking soda, and salt. Whisk together the yogurt and water to combine. Beat the butter and sugar in with an electric mixer at high speed until the mixture is light and fluffy, about 3 minutes. Add the oil, then gradually beat in the eggs, stopping to scrape down the sides of the bowl as needed. Beat in the vanilla. Reduce the mixer speed to low. Starting with the flour mixture, add three equal portions of the flour mixture alternating with two equal additions of the yogurt mixture. After each addition, scrape down the sides of the bowl and increase the mixer speed to high for a few seconds. When the batter is smooth, increase the speed to high and beat for 30 seconds. Spread the batter evenly in the pan and smooth the top. Bake until a wooden skewer inserted deep in the cake comes out clean, about 50 to 55 minutes. Cool and remove from the pan.
To assemble the cake: Split the cake into three even layers and set the top two aside. Spoon about 3/4 cup of the ganache into a pastry bag with a small tip or a small plastic bag and snip off the corners to the desired size, about 1/4 inch. On the bottom layer, pipe a thin line of the cooled ganache around the edge and fill the center with 1/2 cup of the raspberry jam or preserves, spreading it evenly. Repeat with the second layer, then place the top layer on. (You should still have about half the ganache left in the pastry bag to decorate the top). Using a small amount of the ganache, skim coat, spreading a very thin layer of frosting on the top and sides to smooth the cake. Set the cake in the freezer for about 10 minutes to set, remove and frost with the remaining ganache. Arrange raspberries on top in a heart shaped pattern.
*Note- Do not refrigerate ganache or it will lose it's sheen. I set mine in the laundry room, the coolest room in the house, and it is spreadable in about 2 1/2 to 3 hours. It will vary depending on the size of the bowl and the ambient temperature.