Mango Oatmeal Crumble Bars

You know that moment when summer mangoes show up and you panic because you either eat them all in two days or waste them? I made these Mango Oatmeal Crumble Bars the last time I had a mango surplus, and they saved the day — and my dignity. I’ll be honest: I love the crunchy oat crumble and the sweet-tart mango filling. Want something easy, tasty, and impressively homemade? You’re in the right place. Also, if you like oat bars with other flavors, check out this recipe for healthy pumpkin oatmeal bars for a cozy fall twist.

Why You’ll Love This Recipe

• Quick to make: The prep takes under 20 minutes if you work efficiently.
• Great texture contrast: The buttery oat crust meets juicy mango and crunchy topping.
• Family-friendly: Kids usually devour these, no negotiation required.
• Flexible: Use frozen mango in a pinch, or swap in berries if you want variety.
• Keeps well: These bars store nicely, so you can snack without guilt.

Ingredients You’ll Need

Here’s the exact ingredient list so you can shop like a boss. The Ingredient list aligns with the Method below for smooth execution.

• 1/2 cup unsalted butter (melted)
• 1 cup all-purpose flour
• 3/4 cup old-fashioned whole-rolled oats
• 1/2 cup granulated sugar
• 1/4 cup light brown sugar (packed)
• 1/2 teaspoon salt (or to taste)
• 2 cups coarsely chopped fresh ripe mango
• 1/3 cup granulated sugar
• 2 tablespoons lemon juice
• 2 teaspoons corn starch

How to Make (Step-by-Step)

Below I’ll walk you through the Method in short, clear steps. Follow them and you’ll impress yourself.

STEP 1 — Prep the Pan and Oven

Preheat your oven to 350°F. Line an 8-inch square pan with aluminum foil and spray with cooking spray; set aside. Lining the pan helps with cleanup and I highly recommend it — unless you enjoy scrubbing baked-on crumble for fun.

STEP 2 — Make the Crust and Crumble Topping

In a large, microwave-safe bowl melt the butter, about 1 minute on high power. Add the flour, oats, sugars, optional salt, and stir to combine. Expect the mixture to look dry and sandy with some larger, well-formed crumble pieces. Set 1 heaping cup of this mixture aside to be sprinkled on later as the crumble topping. Transfer the remaining mixture to the prepared pan, and using a spatula or your fingers, hard-pack the mixture to create an even, smooth, flat crust; set aside.

STEP 3 — Prepare the Mango Layer

In a large mixing bowl (you can reuse the same one from the crust), add all mango layer ingredients: chopped mango, 1/3 cup granulated sugar, 2 tablespoons lemon juice, and 2 teaspoons corn starch. Toss to combine. If the sugar hasn’t dissolved fully, don’t sweat it — it will liquify while baking. Evenly distribute the mango mixture over the crust. Evenly sprinkle with the reserved heaping 1 cup crumble topping mixture. Before sprinkling, I squeeze the mixture in my palm to encourage bigger crumble pieces to form.

STEP 4 — Bake and Cool

Bake for about 50 minutes, or until the edges look set and the center has just set. The crumble topping should appear set and very pale golden. The mango filling may bubble along the edges. Bars may take longer than 50 to 55 minutes if the mangoes are very juicy, so watch the bars, not the clock, when evaluating doneness. Place pan on a wire rack and allow bars to cool for at least 1 hour before slicing. If you slice them early, they’ll be messy and might fall apart — and yes, I learned that the hard way. Bars will keep airtight at room temperature for up to 1 week, in the fridge for up to 10 days, or in the freezer for up to 6 months. Adapted from Blueberry Oatmeal Crumble Bars and Strawberry Oatmeal Crumble Bars.

Pro Tips for the Best Results

• Use ripe but firm mangoes for the best texture; overripe ones get too juicy.
• Squeeze the crumble into larger clumps for a chunkier topping.
• Taste the mango mixture before baking; add a pinch more sugar if your mangoes taste tart.
• Don’t skip lining the pan — it makes life way easier when you serve.
• Let them cool fully; patience yields cleaner slices and less sad crumbles.
• If you only have frozen mango, thaw and drain excess liquid before using.

Fun Variations & Topping Ideas

Variations:

• Swap mango for peaches or nectarines for a similar sunny result.
• Try mixed berries for a tangy, colorful bar instead.
• Add 1/2 teaspoon ground ginger to the mango mix for a warm zing.

Toppings:

• Sprinkle toasted coconut on top for tropical vibes.
• Add a light vanilla drizzle after cooling for a dessert finish.
• Serve with a scoop of vanilla ice cream — because why not?

Also, if you enjoy mango crumbles in other formats, you might like this quick round-up of mango crumbles for more inspiration.

Storing and Reheating

Store the bars in an airtight container at room temperature for up to 1 week. Refrigerate for up to 10 days if your kitchen runs hot. Freeze in a single layer on a tray, then transfer to a freezer bag for up to 6 months.

To reheat, bring bars to room temperature or warm them in a 300°F oven for 8–10 minutes. You can microwave a single piece for 15–20 seconds if you’re impatient (I don’t judge). If you freeze bars, thaw them overnight in the fridge before reheating.

Leftover ideas

• Chop cooled bars into cubes and toss into yogurt for a crunchy parfait.
• Crumble leftover bars over a salad of fruit and greens for texture.
• Use small chunks as mix-ins for muffin batter if you bake a lot.

Frequently Asked Questions (FAQ)

Can I use frozen mango instead of fresh?

Yes, you can use frozen mango. Thaw the mango and drain excess liquid before mixing. I trust this one because I’ve used frozen mango many times when fresh mangoes go MIA.

What if my mangoes are too juicy?

Add a little more corn starch (up to 1 teaspoon more) to help thicken the filling. You can also bake a few extra minutes to reduce moisture.

Can I make these gluten-free?

You can substitute a gluten-free flour blend and certified gluten-free oats. The texture will differ slightly but still taste great.

How do I cut neat bars?

Chill the bars for at least an hour, then use a sharp knife wiped clean between cuts. Warm the knife under hot water and dry it for cleaner slices if needed.

Conclusion

If you want a dessert that feels both homey and a little fancy without much effort, these Mango Oatmeal Crumble Bars deliver. They balance buttery oats and juicy mango perfectly, and they handle substitutions like a champ. For more inspiration and the original riff on these bars, check the recipe source at Mango Oatmeal Crumble Bars – Averie Cooks. I’d love to hear how yours turn out — leave a comment and a rating so the next baker doesn’t have to guess on timing like I did. FYI, sharing pictures always makes my day.