I make this when I’ve got bananas that are one day past what anyone will eat out of hand. You know the ones. There’s always at least two sitting there getting darker, and this crumble is honestly the best thing to happen to them. It’s warm and caramel-y and the cardamom gives it this perfumy, slightly exotic thing that makes people ask what’s in it.
The whole thing fits in a small toaster oven pan — no need to heat up your main oven for four servings of dessert. If you’ve been sleeping on using your toaster oven for baking, this recipe might change that. You want a toaster oven baking dish that fits properly in your machine — measure your interior rack before you buy, because the sizing varies way more than you’d expect across brands.
Brown butter is the move here. It takes maybe four extra minutes and it makes the crumble taste like something from an actual bakery instead of something you threw together on a Tuesday. The nutty, almost toffee smell it gets is half the reason this dessert works. Cardamom does the rest. I use it in both the banana layer and the crumble so it runs through the whole thing, not just one part.
If you don’t have walnuts, skip them — it’s fine. A sprinkle of flaky salt at the end is less optional in my opinion, but also not the end of the world. Serve it with vanilla ice cream if you have it, or Greek yogurt if you want to pretend it’s breakfast. Either way, you’ll want a toaster oven with a convection setting if you make this regularly — convection crisps the crumble faster and more evenly, though the standard bake setting works perfectly well too.
Toaster Oven Crispy Brown Butter Roasted Banana and Cardamom Oat Crumble
A warm, buttery oat crumble piled over caramelized roasted bananas and scented with cardamom — comes together in one small pan in under 30 minutes and tastes like something you'd order at a bakery.
Ingredients
Roasted Bananas
Brown Butter Oat Crumble
To Serve
Instructions
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Preheat your toaster oven to 375°F (190°C). Use the bake setting if yours has options.
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Make the brown butter for the crumble first. Put the 3 tablespoons of butter in a small saucepan or even a toaster oven-safe ramekin set on the stovetop over medium-low heat. Let it melt, then keep going until it smells nutty and the milk solids turn golden brown — about 3 to 4 minutes. Pull it off the heat immediately and let it cool for 2 minutes.
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In a medium bowl, combine the oats, flour, brown sugar, cardamom, cinnamon, and salt. Pour the brown butter over everything and mix it with a fork until it clumps together unevenly. Stir in the walnuts if you're using them. Set aside.
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Lay the banana halves cut-side up in a small toaster oven-safe baking dish or pan — an 8x6-inch pan works perfectly. Drizzle the melted tablespoon of butter over them, then sprinkle with the brown sugar, cardamom, and salt.
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Scatter the crumble topping over the bananas in an even-ish layer. Don't press it down — loose crumble gets crispier.
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Bake for 18 to 22 minutes, until the crumble is deep golden brown and the bananas have softened and started bubbling around the edges. If your toaster oven runs cool, give it an extra 3 minutes or switch to broil for the last 2 minutes to really brown the top.
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Let it sit for 5 minutes before serving — the banana juices firm up a little and it's easier to scoop. Serve warm with ice cream or yogurt and a pinch of flaky salt on top.
Notes
Bananas: The riper the better. Bright yellow bananas won't give you nearly as much caramel flavor as ones that are heavily spotted or even turning black. Quick oats: Don't use them here. They turn to mush instead of getting that crispy, slightly chewy texture you want. Pan size: If you're using a 6-cup muffin tin instead of a baking dish, divide everything among 4 cups for individual servings — they bake in about 16 minutes. Storage: Cover leftovers and refrigerate up to 2 days. Reheat in the toaster oven at 325°F for about 8 minutes to get the crumble crispy again. The microwave works in a pinch but the topping goes soft.
Nutrition
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Written by
Emma is a home cook who loves coaxing big flavor out of a toaster oven — from crispy roasted vegetables to easy weeknight dinners and sweet treats. She develops and tests Toastera's recipes for small-appliance kitchens.
Reviewed for accuracy & safety · Last updated September 7, 2026 · About Toastera
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