You don't need much more than chocolate and cream to create this indulgent treat. A dollop of solid ganache is hidden in the center of chocolate cake batter and pours out of the single-serve cake after baking. You may not be able to eat just one.
For the ganache: Bring a medium pot of water to a simmer over medium-high heat. Set a heatproof bowl over the water (don't let it touch the water) and add the chocolate, stirring occasionally, until melted. Once melted, add the heavy cream and whisk to combine. Set the bowl aside and allow ganache to cool to room temperature.
For the cake base: Prepare the ramekins by melting 1 tablespoon butter in a small saucepan (or in the microwave) and use a pastry brush to butter the bottom and sides of six 8-ounce ramekins. Add a spoonful of cocoa powder to each, shaking and rotating to evenly coat all sides of the ramekins; tap out excess. Set the prepared ramekins on a baking sheet and set aside.
Set a new bowl over the double boiler. Add the chocolate and remaining 2 sticks butter and let melt, stirring occasionally, until completely smooth. Remove from the heat.
In the bowl of a stand mixer fitted with the whisk attachment, beat together the eggs, egg yolks and sugar until just combined. Add the chocolate-butter mixture and continue to whisk on medium-low speed until the batter is velvety and completely mixed.
Add the flour, cinnamon and cayenne and whisk until fully incorporated.
Fill the ramekins about one-quarter of the way. Add 1 to 2 tablespoons of the ganache to the center of the batter in each ramekin, then top with more batter so each ramekin is three-quarters full. Refrigerate the ramekins for 20 minutes prior to baking.
Bake until the sides are set, 14 to 15 minutes. A toothpick inserted in the middle should come out coated with hot ganache.
Cool for 1 minute then invert the ramekins onto serving plates; wait 10 seconds before lifting to unmold. Gently tap the ramekins and lift straight up to remove.
Top each cake with few raspberries and dust with confectioners' sugar before serving. Serve immediately while still warm.