Shatter-Glazed Grapefruit & Crème Fraîche Slab Cake

Instructions

1. 1

   Preheat your oven to 350°F (175°C). Grease a 9x13-inch quarter-sheet pan or baking dish, then line it with a parchment paper sling, leaving overhang on the long sides for easy lifting.

   5 min

   Tip: Using a metal quarter-sheet pan ensures crisp edges. Glass or ceramic will take longer to bake and won't caramelize the edges the same way.

2. 2

   In the bowl of a stand mixer, combine 1 1/2 cups granulated sugar and 2 tbsp grapefruit zest. Use your fingertips to massage the zest into the sugar until it feels like wet sand and smells extremely fragrant.

   5 min

   Tip: Don't skip this. Rubbing the zest releases the natural essential oils. If you just whisk it in, you leave half the flavor trapped in the rind.

3. 3

   Add 1 cup cultured unsalted butter to the citrus sugar. Using the paddle attachment, beat on medium-high speed for 4 to 5 minutes. Scrape down the bowl halfway through. You want the mixture to turn noticeably pale, fluffy, and increased in volume.

   5 min

   Tip: This is the creaming method in action. We are mechanically forcing air into the fat to give the cake its lift. Rush this, and your crumb will be dense.

4. 4

   With the mixer on medium-low, add 3 large eggs one at a time, letting each incorporate fully before adding the next. Pour in 1/2 cup crème fraîche, 1/4 cup fresh grapefruit juice, and 1 tsp vanilla bean paste. Mix until just combined. It might look slightly curdled—that's fine.

   5 min

   Tip: Room temperature ingredients are non-negotiable here. Cold eggs will seize the aerated butter and break your emulsion.

5. 5

   In a separate bowl, briefly whisk 2 cups all-purpose flour, 1 1/2 tsp baking powder, 1/2 tsp baking soda, and 3/4 tsp kosher salt. Add the dry ingredients to the wet in two additions, mixing on low speed just until the last streaks of flour disappear.

   5 min

   Tip: Finish the mixing by hand with a rubber spatula to ensure you don't overwork the gluten. Scrape the bottom to catch any hidden pockets of butter.

6. 6

   Scrape the batter into your prepared pan, smoothing the top with an offset spatula. Bake for 25 to 30 minutes, or until the edges are golden and the center springs back slightly when pressed. The cake should not jiggle or wobble.

   30 min

   Tip: Rotate the pan at the 15-minute mark if your oven has hot spots.

7. 7

   While the cake bakes, whisk 1 1/2 cups powdered sugar with 3 tbsp fresh grapefruit juice in a small bowl until completely smooth. The glaze should be thick but pourable, like heavy cream.

   5 min

   Tip: If it's too stiff, add more juice a few drops at a time. Too thin? Add a tablespoon more powdered sugar.

8. 8

   Remove the cake from the oven and let it sit in the pan for 5 minutes. While the cake is still warm, pour the glaze evenly over the top. Use an offset spatula to push it all the way to the edges. Immediately sprinkle with 1/4 tsp flaky sea salt.

   5 min

   Tip: Glazing while warm is the secret to a shatter-crisp shell. The heat sets the sugars fast.

9. 9

   Let the cake cool completely in the pan—about 30 minutes minimum. The glaze will turn from shiny to opaque and matte. Once fully set, use the parchment overhang to lift the slab onto a board, slice into neat squares, and serve.

   30 min

   Tip: Wipe your knife between cuts if you want razor-sharp café presentation.