I borrow this recipe from Carla Bartoluccia’s cookbook Einkorn. Recipes For Nature’s Original Wheat. There is one substitution I make and that is I substitute Bellwether Farms Sheep’s milk yogurt for the kefir. They have wonderful yogurt and I am thankful that Whole Foods here in SC carries it. It comes from Sonoma County California. When I do not have an animal in milk I do not keep milk kefir grains. So I find the sheep’s yogurt to be a wonderful substitution. I add three tablespoons of sour dough starter to the yogurt to give it a kick start. So here is the recipe as written in the cookbook and you may make the substitution if you like.
For the cake: 2 1/2 cups (300 g) of all purpose einkorn flour, 2 tsp baking powder, 1/2 tsp baking soda, 1/2 tsp salt, 10 tbsp butter (140 g) @ room temperature. A bit more for buttering the pan. 1/2 cup (100g) granulated sugar, 1/2 cup (110 g) dark brown sugar (packed), 3 large eggs, 1/2 tsp pure vanilla extract, 1 cup kefir (240 g)
For the crumb topping: 3/4c (90g) all purpose einkorn flour, 1/4 c (50 g) granulated sugar1/4 tsp fine sea salt, 6 tbsp (84 g) cold, unsalted butter, cut into 1/4” cubes, 1/4 tsp ground cinnamon, 1/4 tsp unsweetened cocoa powder, powdered sugar for dusting.
Make the cake: Sift together the flour, baking powder, baking soda and the salt in a medium bowl. In the bowl of a standing mixer fitted with the paddle attachment, cream the butter on med-low speed for 2-3 minutes. Add the sugars and mix on med-low speed for another 1-2 minutes until the butter is fluffy and whipped. Add the eggs and vanilla on med-low till mixed. Scraping down sides and bottom of the bowl. Detach bowl from mixer. Using a spatula fold half of the flour mixture into the egg mixture. Fold 1/2 cup of the kefir, then repeat with remaining flour mixture and kefir until everything is just combined. (Do not overwork the batter) Cover the bowl with plastic wrap and store in the refrigerator all night or at least 8 hours. When ready to bake, butter a 9x13” baking dish. Preheat oven to 350 degrees. Remove the batter from the refrigerator and spread into prepared baking dish. Set aside. Make the topping: Mix together the flour, granulated sugar, and the salt in a medium bowl. Cut the butter into the flour mixture with a pastry blender until the butter is completely incorporated leaving only small chunks of butter. The topping can be made at night and stored in the refrigerator with the cake batter. Sprinkle half the mixture on top of the cake. In a small bowl combine the cinnamon and cocoa powder and sprinkle over the topping. Sprinkle remaining topping over the topping. Sprinkle the remaining cinnamon and cocoa. Bake for 42 minutes or until the middle springs back when pressed. Let cake sit in the pan for 1 hour until completely cooled. Dust generously with organic powdered sugar. .