Equipment
Ingredients
Spiced Streusel Topping
- 120 g all-purpose flour
- 100 g light brown sugar, packed
- 85 g unsalted butter, melted and cooled
- 2 g ground cinnamon
- 1 g salt
Rhubarb Layer
- 300 g fresh rhubarb, trimmed and diced into 1cm pieces
- 25 g granulated sugar
- 5 g cornstarch
Cake Base
- 200 g cake flour
- 6 g baking powder
- 2 g baking soda
- 3 g salt
- 113 g unsalted butter, room temperature
- 150 g granulated sugar
- 2 eggs, large, room temperature
- 5 ml vanilla extract
- 120 g sour cream, full fat, room temperature
Nutrition (per serving)
Method
Preheat the oven to 175°C (350°F). Grease a 23cm (9-inch) square baking pan and line the bottom with parchment paper, leaving an overhang for easy removal.
Prepare the streusel: In a medium bowl, whisk together the all-purpose flour, brown sugar, cinnamon, and salt. Pour in the melted butter and mix with a fork until moist clumps form. Refrigerate this mixture while preparing the batter.
Toss the diced rhubarb with 25g granulated sugar and cornstarch in a small bowl. Set aside.
In a separate medium bowl, sift together the cake flour, baking powder, baking soda, and salt.
In the bowl of a stand mixer fitted with the paddle attachment, cream the room temperature butter and 150g granulated sugar on medium-high speed until pale and fluffy, about 3-4 minutes.
Reduce speed to medium. Add eggs one at a time, mixing fully after each addition. Scrape down the sides of the bowl. Add the vanilla extract and sour cream, mixing until just combined.
Reduce mixer speed to low. Add the dry flour mixture in two batches. Mix only until the flour streaks disappear. Do not overmix.
Spread the batter evenly into the prepared pan. Scatter the rhubarb mixture over the top of the batter, pressing the fruit pieces slightly into the surface. Finally, sprinkle the chilled streusel evenly over the rhubarb.
Bake in the center of the oven for 45 to 55 minutes, or until a tester inserted into the center comes out clean or with just a few moist crumbs (avoiding a piece of rhubarb). Ideally, the internal temperature of the cake crumb should reach 93°C (200°F).
Remove from oven and let cool in the pan on a wire rack for at least 30 minutes before lifting out via the parchment paper and slicing.
Chef's Notes
- Room temperature ingredients (butter, eggs, sour cream) are non-negotiable here; they emulsify better, trapping more air for a lighter crumb.
- If using frozen rhubarb, do not thaw it completely before baking, as it will release too much water. Toss it in the cornstarch while still frozen and bake immediately, adding 5 minutes to bake time.
- Cake flour is preferred over all-purpose for the base because its lower protein content yields a velvety, tender crumb that contrasts beautifully with the crunchy topping.
Storage
Refrigerator: 5 days — Store in an airtight container to prevent drying out.
Freezer: 3 months — Wrap individual slices tightly in plastic wrap then foil.
Reheating: Warm gently in a microwave for 10-15 seconds or in a low oven to refresh the crumb.
