Blueberry cake with sour cream filling and coconut topping

We love crumb cakes here in Estonia. Quite a lot. They're cheap, quick, and an excellent way of using up all those jams and preserves and marmalades we're busy making in July and August and September each year. I've stocked my larder with considerable amounts of wild strawberry fridge jam, apricot jam, sour cherry jam with almonds, and cloudberry jam thus far. And while we consume a jar each weekend, spreading generous amounts of last summer's flavour on our Saturday morning pancakes, we still have plenty of jars of canned goodies to spare. That's when you'll make a good old-fashioned Estonian crumb cake with jam filling.

But sometimes you want something different. Although I've got a good variety of crumb cake and blueberry cake recipes up my sleeve, I was immediately drawn to this simple crumb cake with blueberries on Ragne's foodblog (a popular Estonian food blog). I made it couple of times before tweaking a bit. A bit more sour cream in the filling filling makes the cake even creamier, a generous helping of coconut in the topping makes it more flavourful, and a teaspoonful of vanilla in the cream can do no harm either. Note that the cake isn't very sweet - there's less than a cup of sugar, a scant 170 grams, in the whole lot. If you have a really sweet tooth, you may add a wee bit more sugar, but trust me, it's lovely with the amount specified!

Remember: an American cup is about 240 ml and a stick of butter is 113 grams. That - and your high school math - should help you when doing the conversions :)

Blueberry sour cream cake with coconut crumb topping
(Purukook mustikate, hapukoore ja kookoshelvestega)
Serves about 12

Crumb mixture:
180 g all-purpose flour (300 ml)
85 g caster sugar (100 ml)
0.5 tsp baking powder
a pinch of salt
150 g cold butter, cut into cubes
50 g unsweetened desiccated coconut (optional)

Filling:
2 large eggs
85 g caster sugar (100 ml)
250 g sour cream or Greek yoghurt
30 ml all-purpose flour (50 ml)
1 tsp vanilla sugar or extract
200 g blueberries or bilberries

Line a 30x40 cm Swiss roll tin with a parchment paper. Put aside.

Preheat the oven to 180 C/350 F.

Start with the crumb mixture. Mix the flour, sugar, baking powder and salt until combined. Add the cubed butter and pinch with your fingers until a coarse wet sands forms (I usually use my food processor for that).

Take about two-thirds of the mixture and scatter into the baking tin. Press with the palms of your hand until compact.

Whisk eggs with sugar, sour cream/yogurt, flour and vanill until combined. Spread over the base. Scatter blueberries on top.

Fold coconut flakes into the remaining third of the crumb mixture (if using), then scatter the crumbs over the blueberries.

Bake in a preheated oven for about 40 minutes, until the crumb topping is lovely shade of golden brown.

Cool before cutting into small squares and serving.

More crumb cake recipes:
Classic crumb cake with jam filling @ Nami-Nami
Mascarpone and curd cheese crumb cake @ Nami-Nami
Purukook @ Siit nurgast ja sealt nurgast (recipe in Estonian)
Blueberry crumb cake @ The Pioneer Woman

More blueberry cake recipes:
Coconut and blueberry cake @ Nami-Nami
Blueberry cheesecake @ Nami-Nami
Blueberry sour cream tart @ Nami-Nami
French blueberry tart @ Nami-Nami
Buttermilk-blueberry breakfast cake @ Alexandra's Kitchen
Simple blueberry cake @ Bake or Break