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Cast-Iron Rhubarb & Cardamom Crumb Cake

Cast-Iron Rhubarb & Cardamom Crumb Cake

A sharp, tangy rhubarb layer trapped between a lacy crème fraîche batter and a heavily spiced cardamom streusel. Baked in a cast-iron skillet for maximum crust-to-crumb ratio, because we are not suffering for brunch.

Camille Roux
Camille Roux
Prep: 17 minutes
Cook: 45 minutes
8
easy
breakfastdessertsnack
cast-ironsunday-brunchrhubarbstreusel+1

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Timeline

1 hour 2 minutes
0m15m30m45m1h
Prep Oven & Skillet
5m
Mix Cardamom Crumb
5m
Mix Wet Ingredients
5m
Fold Dry Ingredients
Assemble Cake
Bake Crumb Cake
45m

Ingredients

  • 300g (about 3 cups) Rhubarb(Chopped into 1/2-inch pieces across the stalk)
  • 180g (1 1/2 cups) All-purpose flour (for batter)
  • 150g (3/4 cup) Granulated sugar
  • 113g (1/2 cup) Unsalted cultured butter, room temp(Plus extra for greasing the skillet)
  • 120g (1/2 cup) Crème fraîche(Full-fat sour cream works too)
  • 2 Large eggs(Room temperature)
  • 1 tsp Vanilla bean paste
  • 1 1/2 tsp Baking powder
  • 1/2 tsp Baking soda
  • 1/2 tsp Kosher salt
  • 60g (1/2 cup) All-purpose flour (for streusel)
  • 50g (1/4 cup) Light brown sugar
  • 50g (1/4 cup) Unsalted cultured butter, melted(For the streusel)
  • 1 tsp Ground cardamom(Freshly ground if possible)
  • 1/4 tsp Flaky sea salt(Maldon preferred)
  • 1 tbsp Turbinado sugar(For sprinkling on the rhubarb)
  • 1 tbsp extra cultured butter(for greasing the skillet)

Instructions

  1. 1

    Preheat your oven to 350°F (175°C). Smear a 9-inch cast-iron skillet heavily with 1 tbsp extra cultured butter. The cast iron is non-negotiable here; it drives heat into the base instantly, saving us from a soggy bottom.

    5 min

    Tip: If you only have a 10-inch skillet, your cake will be slightly thinner—just pull it from the oven 5 minutes earlier.

  2. 2

    Make the crumb. In a medium bowl, whisk together 60g all-purpose flour (for streusel), 50g light brown sugar, 1 tsp ground cardamom, and 1/4 tsp flaky sea salt. Pour in the 50g melted cultured butter and rake it with a fork until large, wet clumps form. Put it in the fridge.

    5 min

    Tip: Cold streusel holds its shape. Warm streusel melts into a greasy puddle.

  3. 3

    Build the quick batter. In a large mixing bowl, aggressively beat the 113g room temp cultured butter and 150g granulated sugar until light and aerated. Crack in the 2 large eggs one at a time, beating well after each. Scrape down the bowl, then whisk in the 120g crème fraîche and 1 tsp vanilla bean paste.

    5 min

    Tip: If your mixture looks broken or curdled after adding the cold crème fraîche, don't panic. The dry ingredients will bring it back together.

  4. 4

    Add the 180g all-purpose flour (for batter), 1 1/2 tsp baking powder, 1/2 tsp baking soda, and 1/2 tsp kosher salt to the wet ingredients. Fold gently with a spatula just until no dry streaks remain. Overmix this and you’ll end up with a crumb tight like a bad alibi.

    3 min

    Tip: Stop folding exactly when you think it needs two more stirs. The batter will be very thick.

  5. 5

    Scrape the batter into your buttered skillet, coaxing it to the edges. Scatter the 300g chopped rhubarb evenly across the top, pressing the pieces down just slightly. Sprinkle the fruit with 1 tbsp turbinado sugar, then retrieve your streusel from the fridge and scatter the clumps aggressively over the entire surface.

    4 min

    Tip: Do not fold the rhubarb into the batter. The water content will weigh the cake down. Layering it ensures jammy pockets and a pristine, lacy crumb underneath.

  6. 6

    Bake in the center of the oven until the edges are dark golden brown, the streusel is crisp, and the cake barely wobbles when you give the skillet a gentle shake, about 40 to 45 minutes.

    45 min

    Tip: Let it cool in the skillet for at least 30 minutes before scooping or slicing. The residual heat sets the crumb.

Chef's Notes

Cami's shortcut note: You can absolutely make the cardamom streusel up to a week ahead of time. Just keep it in an airtight container in the fridge. Let time do the work. Also, butter is not a garnish here—use the highest-fat cultured butter you can find. The tangy lactic notes in the butter bounce perfectly off the sharp rhubarb and earthy cardamom.

Frequently Asked Questions

How long does Cast-Iron Rhubarb & Cardamom Crumb Cake take to make?

Cast-Iron Rhubarb & Cardamom Crumb Cake takes about 1 hour 2 minutes total. That includes 17 minutes of prep and 45 minutes of cooking.

How many servings does this recipe make?

This recipe makes 8 servings.

What skill level is needed for Cast-Iron Rhubarb & Cardamom Crumb Cake?

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

What ingredients do I need for Cast-Iron Rhubarb & Cardamom Crumb Cake?

The main ingredients are: Rhubarb, All-purpose flour (for batter), Granulated sugar, Unsalted cultured butter, room temp, Crème fraîche, Large eggs, Vanilla bean paste, Baking powder, Baking soda, Kosher salt, All-purpose flour (for streusel), Light brown sugar, Unsalted cultured butter, melted, Ground cardamom, Flaky sea salt, Turbinado sugar, extra cultured butter.

What type of meal is Cast-Iron Rhubarb & Cardamom Crumb Cake?

Cast-Iron Rhubarb & Cardamom Crumb Cake is categorized as: breakfast, dessert, snack.