🥣 Preparation
1/ Bring the butter to room temperature: Take out the amount of unsalted butter needed for the base and let it soften at room temperature.
2/ Prepare the baking pan: Line a 24×24 cm square baking pan with parchment paper or lightly grease the inside with butter.
🥣 Preparing the Rhubarb
3/ Cut and marinate the rhubarb: Peel any tough strings from the rhubarb, cut it into 1 cm slices, and place in a bowl. Add the sugar, cornstarch, and lemon juice, and gently mix. Let sit for 10–15 minutes. If a lot of juice is released, drain the rhubarb in a sieve to remove excess liquid.
🥣 Making the Streusel (Crumble)
4/ Make the crumble and chill: Place the flour, sugar, and cold butter in a bowl. Using your fingertips, rub the butter into the flour mixture until it forms coarse crumbs. A mix of larger and smaller crumbs gives the best texture. Once done, chill the crumble in the fridge to help it stay crisp during baking.
🥣 Making the Base Batter
5/ Cream the butter, sugar, and eggs: Beat the softened butter and sugar with a whisk or hand mixer until light and fluffy. Add the eggs one at a time, mixing well after each addition until smooth.
6/ Add the dry ingredients and combine: Sift in the flour and baking powder. Fold gently with a spatula until just combined. Do not over mix. Spread the batter evenly into the prepared pan and smooth the surface.
🥣 Assembling and Baking
7/ Add the toppings: Evenly scatter the rhubarb over the batter, then generously sprinkle the chilled streusel on top.
8/ Bake: Preheat the oven and bake at 180–190°C (356–374°F) for about 40–45 minutes, or until the top is golden brown. Let the cake cool in the pan, then allow it to cool completely before slicing.
🥣 Finishing Touch (Optional)
9/ Dust with powdered sugar: Once the cake has fully cooled, dust the top with powdered sugar using a fine sieve for a soft, rustic finish.
German-Style Rhubarb Crumble Cake (Streuselkuchen) 🍰
