SERVINGS: 9 servings
Preheat oven to 350 F and line a 8-inch or 9-inch square cake pan with parchment paper.
Beat the milk, egg, and vanilla in a liquid measuring cup.
In a large bowl, whisk together the flour, sugar, baking powder, salt, and some freshly grated nutmeg. Cut in the butter until it looks crumbly. (I like to rub this together with my fingertips.)
Add the milk mixture and stir with a fork until the dough is just combined. Dollop this into the cake pan and spread into an even layer.
Bake for 30 to 35 minutes until the top is golden and a toothpick comes out clean. Let cool in the pan for 10 minutes. Then invert onto a rack and cool completely.
While the cake bakes and cools, add the blackberries and sugar to a large bowl and stir together, mashing some of the berries with a fork. Set aside.
In a medium bowl, beat the heavy cream, creme fraiche, and sugar to stiff peaks with a hand mixer. Set aside in the fridge until the cake is fully cooled.
Invert the cake onto a platter and poke all over with a wooden skewer. Spoon most of the blackberry syrup over the cake so that it seeps into the holes.
Spread the whipped creme fraiche over the top of the cake and top with the blackberries. Drizzle the last bit of blackberry syrup around for decoration. You can also use a round cake pan if you don’t have square.