Blackberry jam crumb cake

Not one to be afraid of massive amounts of ingredients – I have made this cake, after all – I must confess that I almost gave up baking the cake on the photo. Almost. Reading the recipe with a calculator on hand I shrieked at the idea of using nearly 400g of butter, 500g of sugar and – my goodness – over 700g of flour in one single cake; a recipe that would pretty much empty my entire pantry. :)

But then I thought that the cake would be huge and that I would be cutting it in several squares to feed all my coworkers – twelve of them – so I decided that they could handle 60g of flour each + a little butter and sugar. To this day no one has complained about it – and I found this cake one of the tastiest I’ve baked so far.. ;)

Blackberry jam crumb cake
slightly adapted from The Weekend Baker, inspired by Valentina’s cake

Topping:
1 cup (2 sticks/226g) unsalted butter, chopped
½ cup (100g) granulated sugar
¾ cup (132g) light brown sugar, packed
1 ½ teaspoons ground cinnamon
¼ teaspoon freshly ground nutmeg
pinch of salt
2 ½ cups minus 1 tablespoon (340g) all purpose flour

Cake:
2 ¾ cups (385g) all purpose flour
1 ¼ cups + 2 ½ tablespoons (280g) superfine sugar
1 ½ teaspoons baking powder
½ teaspoon salt
2 large eggs
1 cup (240ml) buttermilk*
¾ cup (170g) unsalted butter, melted and cooled slightly
2 teaspoons vanilla extract
1 cup blackberry jam – or use your favorite flavor

Start by making the topping: in a large saucepan, melt the butter over medium heat. Remove from the heat and add the granulated sugar, brown sugar, cinnamon, nutmeg and salt. Stir well and break up any sugar lumps. Add the flour and mix until well blended and pasty. Put it in the fridge while you make the batter.
Preheat the oven to 180°C/350°F. Butter a 32x22cm (13x9in) baking pan**.
Now, the batter: in a large bowl, combine the flour, superfine sugar, baking powder and salt. Combine them thoroughly. In a medium bowl, whisk together the eggs, milk, butter and vanilla until well combined. Pour the wet ingredients over the dry ingredients and gently stir with a rubber spatula just until blended – do not overmix. Pour the batter into the prepared pan and smooth the surface. Gently spread the jam over the batter. Top the jam layer with the topping, breaking up the pieces as you go, sprinkling it evenly over the jam, forming a generous layer.
Bake until the cake springs back when lightly pressed and a skewer inserted in the center of the cake comes out clean, 40-50 minutes. Remove from the oven and set the baking pan over a wire rack. Cool completely before slicing and serving.

*homemade buttermilk: place 1 tablespoon lemon juice in a 240ml-capacity measuring cup and complete with whole milk. Wait 10 minutes for it to thicken, then use the whole mixture in your recipe

** I made the exact recipe above using a 20x30cm (8x12in) pan

Serves 15-18