Description
Looking for a delicious way to use your sourdough discard and fresh rhubarb? Moist Rhubarb Sourdough Discard Cake is a tender, tangy-sweet dessert that combines the tartness of rhubarb with a soft, lemony cake, all enhanced by the subtle tang of sourdough discard.
Ingredients
This Rhubarb Sourdough Discard Cake uses pantry staples and fresh rhubarb for a flavorful, moist cake. Here’s what you need and why each one matters:
- Fresh Rhubarb (8 ounces, ~2 cups): Provides tart flavor and visual appeal; ¾ cut into ½-inch chunks for the batter, the rest into longer pieces for a decorative top pattern.
- All-Purpose Flour (170 grams, ~1⅓ cups): Forms the cake’s structure; lightly coats rhubarb to prevent sinking.
- Baking Powder (1½ teaspoons): Ensures a tender, risen crumb.
- Fine Salt (½ teaspoon): Balances sweetness and enhances flavors.
- Cane Sugar (155 grams, ~¾ cup, divided): Sweetens the cake (145 grams in batter, 10 grams for topping) and adds a slight crunch on top.
- Sunflower or Grapeseed Oil (½ cup): Keeps the cake moist and tender, with a neutral flavor.
- Lemon Zest (2 teaspoons): Adds bright, citrusy aroma to complement rhubarb.
- Eggs (2, room temperature): Bind the batter and add richness; room temperature ensures even mixing.
- Runny Honey (2½ tablespoons): Adds natural sweetness and moisture with a subtle floral note.
- Sourdough Discard (65 grams, ~¼ cup, preferably room temperature): Contributes slight tang and moisture, reducing waste.
- Vanilla Extract (1½ teaspoons): Enhances flavor with warm, sweet notes.
- Fresh Lemon Juice (1 tablespoon): Boosts tartness and balances sweetness.
- Whole Milk (2½ tablespoons): Adds moisture and tenderness to the crumb.
Substitutions and Variations
- Rhubarb: Use frozen rhubarb (thawed, drained, and patted dry); substitute ½ cup chopped strawberries or raspberries for part of the rhubarb (adjust sugar down by 1 tablespoon).
- Flour: Swap for gluten-free 1:1 baking flour for a gluten-free version; ensure proper weight (170 grams).
- Baking Powder: Ensure fresh for proper rise; no substitute without altering texture.
- Cane Sugar: Use granulated sugar or coconut sugar (may darken flavor); reduce topping sugar for less crunch.
- Oil: Replace with melted butter or avocado oil; butter adds richer flavor but may firm up when cold.
- Lemon Zest/Juice: Swap for orange zest/juice or omit zest (use ½ teaspoon more vanilla for flavor).
- Eggs: Use flax eggs (2 tablespoons ground flaxseed + 5 tablespoons water, let sit 5 minutes) for vegan, but texture may be denser.
- Honey: Substitute with maple syrup or agave nectar; honey adds unique flavor.
- Sourdough Discard: Use active sourdough starter (same amount) or increase flour by 30 grams and milk by 2 tablespoons if no discard (lose tangy flavor).
- Vanilla Extract: Omit or use ½ teaspoon almond extract for a twist.
- Milk: Swap for plant-based milk (e.g., almond, oat) for dairy-free; whole milk adds richness.
- Add-Ins: Mix in ¼ cup chopped walnuts or ½ teaspoon cinnamon to the batter for extra texture or warmth.
Pro Tip: Weigh ingredients (e.g., 170 grams flour, 65 grams discard) for accuracy, as volume can vary. Use room-temperature eggs and discard for a smoother batter; trim rhubarb’s woody ends for best texture.
Instructions
- Prepare the Oven and Pan:
- Preheat oven to 350°F (177°C).
- Grease an 8-inch or 9-inch square cake pan and line with parchment paper, leaving overhang for easy removal.
- Tip: Ensure parchment covers the bottom and sides; grease lightly under and over parchment for extra insurance.
- Prep the Rhubarb:
- Trim and cut 8 ounces rhubarb: ¾ (6 ounces, ~1½ cups) into ½-inch chunks, the rest into longer pieces (2-3 inches) to fit diagonally across the pan for decoration.
- Place chunks in a medium bowl.
- Tip: Cut rhubarb uniformly for even baking; save prettiest pieces for the top pattern.
- Mix Dry Ingredients:
- In another medium bowl, whisk 170 grams all-purpose flour, 1½ teaspoons baking powder, and ½ teaspoon fine salt.
- Scoop 2 heaping teaspoons of this mixture into the bowl with the rhubarb chunks and toss to coat (prevents sinking in batter). Set both bowls aside.
- Tip: Toss rhubarb gently; a light flour coating is enough.
- Make the Batter:
- In a stand mixer (or large bowl with a hand mixer), beat 145 grams cane sugar, ½ cup sunflower or grapeseed oil, and 2 teaspoons lemon zest on medium speed for 1 minute until slightly frothy and sugar begins to dissolve.
- Add 2 room-temperature eggs and beat on medium for 30 seconds until frothy and well combined.
- Add 2½ tablespoons runny honey, 65 grams sourdough discard, 1½ teaspoons vanilla extract, 1 tablespoon fresh lemon juice, and 2½ tablespoons whole milk. Mix on medium speed until just combined, about 15 seconds.
- On low speed, gradually add the dry flour mixture, mixing just until no flour streaks remain (do not overmix).
- Tip: Scrape the bowl as needed; stop mixing once flour is incorporated to keep the cake tender.
- Fold in Rhubarb:
- Gently fold the flour-coated rhubarb chunks into the batter using a spatula. It’s okay if some flour is visible on the rhubarb.
- Tip: Fold carefully to avoid crushing rhubarb; ensure even distribution.
- Assemble the Cake:
- Pour the batter into the prepared pan and smooth the top with a spatula.
- Arrange the longer rhubarb pieces on top in a decorative pattern (e.g., diagonal lines or a lattice).
- Sprinkle the top evenly with the remaining 10 grams (2 heaping teaspoons) cane sugar for a crunchy finish.
- Tip: Press rhubarb pieces lightly into the batter; sugar adds sparkle and texture.
- Bake the Cake:
- For an 8-inch pan: Bake at 350°F for 25 minutes, then reduce oven to 330°F (166°C) and bake 15 minutes more, until a toothpick inserted in the center comes out with a few moist (not wet) crumbs.
- For a 9-inch pan: Bake at 350°F for 20 minutes, then reduce to 330°F and bake 8-10 minutes more, until a toothpick tests similarly.
- Tip: Check doneness early to avoid overbaking; tent with foil if the top browns too quickly.
- Cool and Serve:
- Remove the cake from the oven and cool in the pan on a cooling rack for 30 minutes.
- Lift the cake out using the parchment overhang, slice, and serve warm or at room temperature (makes 9-12 servings).
- Store in a sealed container in the refrigerator for up to 4 days.
- Tip: Let cool slightly for cleaner slices; serve with whipped cream or yogurt for extra indulgence.
Cooking Tips:
- Prevent Overbaking: Check with a toothpick early; moist crumbs indicate doneness, while a wet batter needs more time.
- Rhubarb Placement: Arrange top rhubarb pieces thoughtfully for a pretty presentation; avoid overlapping too much.
- Mix Gently: Overmixing the batter can make the cake dense; fold rhubarb with care to maintain tenderness.