You don't need an oven to make this delicious cake. A pile of crêpes filled with berry sauce and chocolate ganache - simple concept, easy to execute, and perfect for Valentine's Day.
Whisk or mix together the flour, salt and sugar. Set aside. Mix the eggs, milk and vanilla. Then pour the flour mixture into the liquid and blend, by hand with a whisk, or with a blender or immersion blender.
Add the melted butter, stir to combine, and refrigerate the batter (covered) for at least one hour. This resting time for the batter is crucial. Meanwhile, make the fillings.
Mix berries, sugar, lemon juice and zest in a medium saucepan. Bring to a simmer and stir to dissolve the sugar.
Puree in a blender or using an immersion blender until all the berries are completely mashed and the raspberry or strawberry seeds (if using those berries) are mostly blended into the fruit. Set the sauce aside to cool.
Heat the cream beyond a simmer, to a boil but not rolling. Pour it over the chocolate in a medium-small bowl and let it rest for a few minutes. Then gently fold or mix the cream and chocolate with a spatula until they are a uniform color.
Heat a crêpe pan or, if you don't have one, a pan with very shallow sides. With an oil-moistened paper towel, rub the pan. Take the batter out of the refrigerator.
Pour in the first ladle-full of batter. Spread it around the pan by lifting the pan up and tilting it. Pour out any remaining batter. (I don't worry if the batter hangs over the edge of the pan once you pour the excess off.) Cook it for maybe two minutes or so, until the center is slightly brown, then flip the crêpe. Cook the second side for just a minute or so, then slide the crêpe onto a clean plate.
To make the cake, place one crepe on a plate or platter. Add a large dollop of room temperature ganache or berry sauce, spread it over the crêpe, and put another crêpe on top.
Remember mise en place? Crêpe-making is a breeze if you have all your materials at hand when you begin. If your chocolate ganache is not pourable, you can re-heat it in a double boiler, on top of a bowl of simmering water, or by microwaving it in short bursts at a low temperature. I'm a microwave-heating fan because it's simple. However, you do have to be careful not to burn the chocolate when microwaving.
If you do use jars of chocolate and/or berry sauce, you may need to use heated milk or cream in the case of the ganache, or juice in the case of the berry sauce, to dilute them enough to make them spreadable.
The berry sauce I made is adapted from "Mixed Berry Sauce" at The Spruce. I use less sugar, but you should definitely decide how much sugar to use based on the particular type of berries, how sweet your berries are, and how sweet you like your berry sauce.