Rhubarb Coffee Cake with Blackberries and Big Crumb Topping

Rhubarb Coffee Cake with Blackberries and Big Crumb Topping

By Irvin Lin

This spring coffee cake takes awhile to bake. That’s because it’s weighed down with both the fruit (a mix of rhubarb and blackberries) as well as a lot of crumb topping. And when I say a lot of crumb topping, I’m talking about half the pan is crumb topping. But the end result is a lovely coffee cake that is not too sweet and perfect for breakfast or a coffee/tea break.

A few things to note: The crumb topping uses graham flour, a coarse milled whole wheat flour. If you don’t have it, feel free to substitute whole wheat or regular all-purpose flour in its place. Don’t use frozen rhubarb or blackberries though. They shed too much water. And finally make sure the butter is at room temperature before you start. If it’s too cold it won’t incorporate into the dry ingredients properly. If you forget to bring it to room temperature, check out my tip on bringing butter to room temperature fast.

Adapted from a New York Times recipe.

Ingredients
Fruit Mix-In
3/4 pounds rhubarb, cut into 1-inch chunks
1 pint (6 ounces) blackberries
2 tablespoon flour
1 teaspoon ground ginger
1 tablespoon diced crystallized ginger

Crumb Topping
2/3 cup (150 g) packed dark brown sugar
2/3 cup (135 g) granulated white sugar
2 teaspoon cinnamon
1 teaspoon cardamom
1/2 teaspoon nutmeg
1/4 teaspoon kosher salt
2 cups (280 g) all-purpose flour
1 1/4 cups (190 g) graham flour or whole wheat flour,/span>
1 cup (225 g or 2 sticks) unsalted butter, melted

Cake Batter
2/3 cup (150 g) sour cream
2 large eggs
2 large egg yolks
1 tablespoon vanilla extract
2 cups (280 g) all-purpose flour
1 1/4 cups (250 g) granulated white sugar
1 teaspoon baking powder
1 teaspoon baking soda
1/2 teaspoon kosher salt
3/4 cup (170 g or 1 1/2 sticks) unsalted butter, at room temperature

Directions
1. Preheat an oven to 325ºF. Spray a 9 x 13 x 2 inch baking pan with cooking spray.

2. Place the rhubarb and blackberries in a medium bowl and sprinkle the flour, ground ginger and crystallized ginger over it. Toss to coat (it’s OK if there is leftover dry ingredients at the bottom of the bowl). Set aside.

3. Make the crumb topping by placing both sugars, spices, salt and flours in a bowl and stir vigorously with a whisk. Drizzle the butter over the dry ingredients and toss with a large spatula until the liquid is absorbed and it all starts to clump up.

4. Make the cake batter by placing the sour cream in a medium bowl and adding the eggs, egg yolks and vanilla. Stir to combine. Place the flour, sugar, baking powder, baking soda and salt in the bowl of stand mixer fitted with a paddle attachment. Stir on slow speed until the dry ingredients are blended. Then add the butter, 2 tablespoon at a time, until incorporated. Stir on low speed until the dry ingredients start to take on the texture of wet sand and there are no more butter lumps. With the mixer still on slow speed, slow pour and scrape in the sour cream. Beat until a cream batter forms.

5. Scrap most of the batter into the pan, reserving about 1 cup of the batter in the bowl. Spread the batter evenly over the pan (it will seem thin). Sprinkle the fruit mix-in over the cake batter, making sure to sprinkle over any dry ingredients that may be in the bottom of the fruit bowl. Then spread the reserve cake batter over the fruit. Don’t worry if you can’t spread it evenly over the fruit. Do the best you can.

6. Sprinkle the crumb topping over the fruit. You’ll have a lot of it so make sure it’s evenly covers the cake. Bake the cake for 80 to 90 minutes or until a toothpick inserted into the cake all the way to the bottom comes out clean. Because there’s a large crumb topping, I actually found the best way to make sure the cake is done is to insert a thermometer into the pan and test the cake by temperature. Once the center of the cake hits 210ºF, the cake is done. Let cool in the pan before serving.

Makes 12 to 16 servings.