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Brown Butter, Blackberry & Hazelnut Custard Slab

Brown Butter, Blackberry & Hazelnut Custard Slab

Technically, this is a flognarde—a French clafoutis made with anything but cherries. But we don't care about semantics on a Sunday; we care about contrast. Think blistered, buttery edges, a silken custard center that wobbles just right, and tart summer blackberries cutting through the crunch of toasted hazelnuts. This is café-level output with blender-level effort, because we're not suffering for brunch.

Camille Roux
Camille Roux
Prep: 15 minutes
Cook: 25 minutes
6
easy
breakfastdessert
custard-bakesunday-brunchflognardesheet-pan+1

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Timeline

53 minutes
0m15m30m45m53m
Preheat Oven & Pan
15m
Brown the Butter
5m
Blend Batter Base
Incorporate Butter & Rest
8m
Prep Hot Pan
Pour Batter & Top
Bake the Slab
25m
Cool & Set
10m

Ingredients

  • 5 tbsp Cultured butter (unsalted)(Divided (4 tbsp for browning, 1 tbsp for the pan))
  • 4 large Eggs(Room temperature preferred)
  • 1 cup Whole milk
  • 1/2 cup Heavy cream(Do not swap for low-fat; we need the richness for a lacy crumb)
  • 1/2 cup All-purpose flour
  • 1/3 cup + 1 tbsp Granulated sugar(Divided (1/3 cup for batter, 1 tbsp for topping))
  • 1/2 tsp Kosher salt
  • 1 Lemon(Zested)
  • 2 cups Blackberries(Fresh, dry, and plump)
  • 1/2 cup Hazelnuts(Blanched, toasted, and roughly chopped)
  • 1 whole lemon zest of 1 lemon(Used in step 3, but only 'Lemon (1)' is listed in ingredients.)

Instructions

  1. 1

    Place your quarter sheet pan or 10-inch cast-iron skillet into the cold oven. Preheat to 400°F (200°C). Let the pan get screeching hot along with the oven. That initial sizzle is what builds the crust-to-crumb ratio we obsess over.

    15 min

    Tip: A cast-iron or heavy aluminized steel sheet pan conducts heat best.

  2. 2

    In a small skillet, melt 4 tbsp cultured butter (unsalted) over medium heat. Let it pop and foam until it smells intensely nutty and toasted brown bits form at the bottom. Pour into a small bowl to cool slightly. Butter is not a garnish; this is your flavor foundation.

    5 min

    Tip: Watch it closely—butter goes from perfect noisette to burnt in seconds.

  3. 3

    In a blender, combine 4 large eggs, 1 cup whole milk, 1/2 cup heavy cream, 1/2 cup all-purpose flour, 1/3 cup granulated sugar, 1/2 tsp kosher salt, and zest of 1 lemon. Blend on medium-high until aggressively smooth and aerated.

    2 min

    Tip: If you don't have a blender, a vigorous whisking in one bowl works just fine—just ensure there are zero lumps.

  4. 4

    With the blender running on its lowest speed, slowly stream in the cooled browned 4 tbsp cultured butter (unsalted), making sure to scrape in every single toasted milk solid. Let the batter rest while the oven finishes preheating. This brief hydration ensures the crumb doesn't end up tight like a bad alibi.

    8 min

  5. 5

    Carefully pull the scorching pan from the oven. Instantly drop in the remaining 1 tbsp cultured butter (unsalted), swirling to coat the bottom and sides as it aggressively foams. Scatter 2 cups blackberries evenly across the sizzling surface.

    2 min

    Tip: The pan is blazing hot; use quality oven mitts and work quickly.

  6. 6

    Pour the rested batter directly over the fruit. Quickly scatter 1/2 cup hazelnuts and the remaining 1 tbsp granulated sugar over the top for a shattered, crunchy crust.

    1 min

  7. 7

    Bake until the edges are violently puffed, curled, and deeply bronzed, and the center has a distinct, confident jiggle—about 25 minutes. You want a wobble, not a slosh.

    25 min

    Tip: Do not open the oven door during the first 15 minutes or you'll sacrifice the puff.

  8. 8

    Remove from the oven. The dramatic puff will immediately begin to collapse into a rustic, lacy custard. Let time do the work; cool it for at least 10 minutes before slicing so the custard sets.

    10 min

    Tip: Serve warm or at room temperature. A dusting of powdered sugar is optional but welcome.

Chef's Notes

Cami's shortcut note: The fridge is your friend here. You can blend the batter (everything through step 4) the night before and let it chill. Hydrating the flour overnight gives you an even creamier, silkier custard that puffs dramatically when it hits the hot pan. Just give it a quick whisk before pouring. Don't skip preheating the pan—that initial shock of heat is non-negotiable.

Frequently Asked Questions

How long does Brown Butter, Blackberry & Hazelnut Custard Slab take to make?

Brown Butter, Blackberry & Hazelnut Custard Slab takes about 40 minutes total. That includes 15 minutes of prep and 25 minutes of cooking.

How many servings does this recipe make?

This recipe makes 6 servings.

What skill level is needed for Brown Butter, Blackberry & Hazelnut Custard Slab?

This recipe is rated easy — it's beginner-friendly and straightforward.

What ingredients do I need for Brown Butter, Blackberry & Hazelnut Custard Slab?

The main ingredients are: Cultured butter (unsalted), Eggs, Whole milk, Heavy cream, All-purpose flour, Granulated sugar, Kosher salt, Lemon, Blackberries, Hazelnuts, zest of 1 lemon.

What type of meal is Brown Butter, Blackberry & Hazelnut Custard Slab?

Brown Butter, Blackberry & Hazelnut Custard Slab is categorized as: breakfast, dessert.