"For a really good crumb cake, you need to have yeast dough."
Almost every week growing up, we would have an Entenmann's crumb cake. I loved those things, and it wouldn't last long in our house. We made sour cream coffee cake all the time, but it's not the same (although I love that, too!). Well, years ago, while reading a women's magazine in a doctor's office, there it was. A crumb cake recipe of German origin, typically made by emigrants in the Brooklyn section of New York. And guess what? That little baked-good company my family helped keep in business was a German bakery opened in yes, Brooklyn N.Y. in 1898. I found what I was searching for! A couple years ago, I couldn't locate the clipping, and had to do some research to duplicate it, because, although I could remember the ingredients and procedure, I could not remember the exact amounts. Cook's Illustrated had a recipe that was close, I just had to change an ingredient and tweak the procedure.
When you read through the recipe, don't be thwarted by using the lemon juice to curdle the buttermilk, that is the magic element that gives it that distinct flavor. Don't worry, it doesn't end up tasting like lemon or sour or anything like that. It is just fabulously delicious, moist, buttery and perfectly crumbed. The cake I made this morning is already gone, except for the one piece I hid for myself for tomorrow morning (don't judge me).
Also, although it is a yeast dough, it requires no kneading and is just as easy as any sour cream coffee cake, it simply needs time to raise. Conveniently enough, you can do the second rising in the fridge overnight, and bake it fresh in the morning. That's what I did!
German Crumb Cake
Adapted from a Cook's Illustrated recipe
1 package active dry yeast
1 cup buttermilk
1/2 cup, plus 1 tablespoon sugar
1 tablespoon fresh lemon juice
3 3/4 cups all-purpose flour
1 1/2 teaspoons salt
2 large eggs, at room temperature (this is very important)
1 1/2 teaspoons vanilla
3/4 cup butter, melted
1 1/2 cups flour
3/4 cup sugar
2 teaspoons cinnamon
1 1/2 sticks cold butter, cut into small pieces
1 teaspoon vanilla
Confectioner's sugar for dusting
In a small saucepan, heat buttermilk until warm to the touch. Be careful not to let it boil, or get too hot (over 115 degrees) or it will kill the yeast. Stir in sugar and yeast. Set aside for about 5 minutes to proof the yeast. It should start to get foamy, which means the yeast is working.
Add lemon juice to yeast mixture and let stand until curdled, about 1 minute. In a large bowl, add 3 3/4 cups of flour and salt. Add yeast mixture, melted butter, eggs, and vanilla. Beat with electric mixer on low until just combined, then continue beating on medium until dough is silky and elastic, about 5 minutes. Dough will be very sticky. Leave dough in bowl and sprinkle with two tablespoons flour. Cover bowl with plastic wrap and let dough rise in a draft-free place at warm room temperature until doubled in bulk, 1 1/2 to 2 hours.
Pulse together topping ingredients in a a food processor until many large clumps form. Transfer to a bowl and chill, covered, until ready to use.
Grease a 13x9-inch baking dish. Stir down dough, then spread evenly in the prepared baking dish.
Sprinkle dough with half the crumb mixture, then cover dish with plastic wrap and let rise in a draft free place at warm room temperature until almost doubled in bulk, 1 1/2 to 2 hours. (OR place in the fridge to do this second rising overnight.)
Preheat oven to 350 degrees. Sprinkle remaining topping evenly over the cake and bake 50-60 minutes, until topping is golden brown. Cool cake in pan on a rack until barely warm, then dust lightly with confectioner's sugar and cut into squares.