Rhubarb Cake with Streusel (Rhabarberstreusel)

Sift together flour, sugar and salt in the bowl of a standmixer. Add in the yeast mixture, lemon zest, egg and butter, then knead for 5 to 10 minutes or until you end up with a smooth dough that does not stick to the sides of the bowl. Cover and let rise in a warm spot until the dough has doubled to 1½ its size, about 1 hour.

Using your hands, spread out onto a half sheet baking pan prepped with parchment paper.

Trim the ends of the rhubarb and cut it into 1 in (about 2 cm) pieces. You do not need to peel or boil the rhubarb (see my note below). Evenly cover the dough with it. You can optionally sprinkle a little sugar on top like my Oma did (but I think the streusel adds enough sweetness).

For the streusel, combine all ingredients and using an electric mixer, beat until the dough is combined and starts crumbling apart. Spread out over the rhubarb

Bake at 390℉ (200℃) for about 30 minutes, or until the edges are browned and the streusel start to brown (a toothpick should come out clean after baking).

Cut into 16 squares and serve with freshly whipped cream (I add a little powdered sugar to sweeten and some vanilla extract). Keep the whipped cream cool until ready to serve.