Rhubarb Ginger Upside-Down Oatmeal Cake with Brown Sugar
A rustic upside-down cake featuring tender rhubarb slices caramelized in brown sugar with warming fresh ginger. The oat-enriched batter creates a hearty, moist crumb that balances the tart rhubarb beautifully. Perfect for spring entertaining or cozy family desserts, this cake showcases seasonal rhubarb in an approachable format. The cast iron skillet cooking method ensures even caramelization and easy serving, while the oats add wholesome texture and subtle nuttiness that complements both the bright rhubarb and spicy ginger notes.
Ingredients
- 2 ¼ cups fresh rhubarb, 1/2 inch slicesfrozen rhubarb, thawed and drained1:1vegetariangluten-free-adaptable
thaw completely and drain excess liquid
Full guide → - 1 tablespoon fresh ginger, grated
- 1 cup brown sugar
- ¼ cup unsalted butter
- ½ cup thick cut rolled oats
- ¾ cup boiling water
- ¼ cup unsalted butter, 1/4 inch cubes
- ½ teaspoon vanilla
- 1 large egg
- ½ cup brown sugar
- ½ cup sugar
- 1 cup unbleached all-purpose flourgluten-free flour blend1:1gluten-freegluten-free
use 1:1 baking blend
- 1 teaspoon baking powder
- ¼ teaspoon baking soda
- ¼ teaspoon salt
Instructions
- 1
Combine oats with boiling water in mixing bowl, add cubed butter and set aside to cool
- 2
Preheat oven to 350 degrees and melt butter in 10 inch cast iron skillet
- 3
Remove skillet from heat, spread brown sugar evenly across bottom
- 4
Mix ginger and rhubarb in large bowl, spread evenly over brown sugar in skillet
- 5
Combine flour, baking powder, baking soda and salt in the empty rhubarb bowl
- 6
Add egg, both sugars and vanilla to cooled oatmeal mixture, mix to combine
- 7
Add dry ingredients to wet ingredients, mix until just combined
- 8
Spread batter evenly over rhubarb in skillet
- 9
Bake for 30-40 minutes until done
- 10
Cool for 5 minutes, invert onto cake plate and cool 20 minutes before slicing
Tips
Use a well-seasoned cast iron skillet to prevent sticking and ensure even caramelization of the brown sugar base.
Let the oatmeal mixture cool completely before adding eggs to prevent them from cooking and creating lumps in the batter.
Check doneness with a toothpick inserted in center - it should come out with just a few moist crumbs attached.
Good to Know
Cover and store at room temperature for up to 3 days or refrigerate for up to 1 week
Can be made 1 day ahead and stored covered at room temperature
Serve warm or at room temperature, optionally with whipped cream or vanilla ice cream
Common Mistakes
Don't skip the cooling time before inverting to avoid the cake falling apart
Use fresh rhubarb rather than frozen to prevent excess moisture from making the cake soggy
Substitutions
Dairy-Free Swaps
Gluten-Free Swaps
thaw completely and drain excess liquid
use 1:1 baking blend
General Alternatives
FAQ
Can I use frozen rhubarb instead of fresh?
Yes, but thaw completely and drain excess liquid first to prevent the cake from becoming too wet and affecting the texture.
What if I don't have a cast iron skillet?
Use a 9-inch cake pan, but melt butter separately and pour into pan with brown sugar before adding rhubarb.
How long will this cake keep?
Store covered at room temperature for 3 days or refrigerated for up to 1 week. Best served within first 2 days.