Grapefruit Crumb Cake

Recipe Overview

• Total Time: 1 hour 30 minutes (prep + baking)

• Rating: 4.0 (283 reviews)

• Comments: 40 reviews available

• Servings: 8–10 servings

• Difficulty: Moderate

Ingredients

For the Grapefruit Cake Layer:

• 1 cup (226g) unsalted butter, softened (for cake)

• 1 cup (200g) granulated sugar

• 2 large eggs, room temperature

• 2 cups (250g) all-purpose flour

• 1½ teaspoons baking powder

• ½ teaspoon fine sea salt (omit if substituting fruit; see Notes)

• ½ cup (120ml) whole milk, room temperature

• 1½ cups (225g) fresh grapefruit: sectioned (about 2 large grapefruits) + ¼ cup fresh grapefruit juice (reserve juice for batter)

• 1 teaspoon vanilla extract (optional, for depth of flavor)

For the Almond-Brown Sugar Crumb Topping:

• ½ cup (113g) unsalted butter, softened

• ½ cup (100g) packed light brown sugar

• ¼ cup (30g) almond flour

• ½ cup (60g) all-purpose flour

• ¼ teaspoon ground cinnamon (optional, for warmth)

Instructions

1. Preheat & Prepare the Pan

• Preheat oven to 350°F (175°C). Lightly grease a 10-inch springform pan (or a 10-inch cake pan with ≥1.5-inch depth) with butter or non-stick spray. Line the bottom with parchment paper (for springform pans, secure parchment to the bottom with a strip of tape).

2. Prepare the Grapefruit Cake Batter

• In a large mixing bowl, beat the softened butter and granulated sugar with an electric mixer on medium speed until light and fluffy (2–3 minutes).

• Add eggs one at a time, beating well after each addition.

• In a separate bowl, whisk together flour, baking powder, and salt (if using).

• Alternate adding the dry ingredients and milk to the butter-sugar mixture, beginning and ending with the dry ingredients. Mix on low speed until just combined (do not overmix—small lumps are okay).

• Gently fold in the grapefruit sections and ¼ cup reserved grapefruit juice. Stir in vanilla extract (if using).

3. Prepare the Crumb Topping

• In a medium bowl, combine softened butter, brown sugar, almond flour, all-purpose flour, and cinnamon (if using).

• Use fingertips or a fork to work the mixture into coarse crumbs (some small clumps are acceptable; this ensures texture).

4. Assemble & Bake

• Transfer the grapefruit batter to the prepared pan, spreading evenly with a spatula.

• Sprinkle the crumb topping over the batter, distributing it gently (pat lightly to ensure partial adherence to the batter).

• Bake for 45–50 minutes, or until a toothpick inserted into the center emerges with moist crumbs (not wet batter). The top should be golden brown.

• Remove from oven and let cool in the pan for 15–20 minutes before serving (or serve directly from the pan if using a regular cake pan).

Notes

• Fruit Substitutions: For a balanced tartness, replace 1.5 cups of grapefruit with other tangy fruits (e.g., oranges, tangerines, lemons). Avoid overly sweet fruits like blueberries, peaches, or Bing cherries. If substituting, omit the salt in the cake batter.

• Pan Options: Without a springform pan, use a 10-inch cake pan (≥1.5-inch depth). Bake directly in the pan and serve from it (no need to unmold).

• Salt’s Role: The ½ teaspoon salt enhances grapefruit’s natural tartness. For sweeter substitutes, skip the salt to maintain balance.

• Storage: Store leftover cake in an airtight container at room temperature for up to 3 days, or refrigerate for up to 1 week. Let sit at room temperature for 15 minutes before serving to restore texture.

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