Preheat the oven to 350°F (175°C) and line an 8×8 inch baking pan with parchment paper.

In a medium bowl, combine the diced mango chunks, granulated sugar, and cornstarch. Stir well and set aside.

In a large bowl, whisk together the flour, baking powder, and salt.

Add the cold cubed butter to the flour mixture. Using a food processor or pastry cutter, cut the butter into the flour until small crumbs form.

In a separate bowl, mix the brown sugar, egg, and vanilla extract.

Add the wet ingredients to the crumb mixture and stir until combined. The mixture should remain slightly crumbly.

Press about two-thirds of the crumb mixture into the bottom of the prepared baking pan to form the crust.

Spread the mango filling evenly over the crust layer.

Sprinkle the remaining crumb mixture over the mango filling.

Bake for 35–40 minutes or until the top becomes golden brown.

Remove from the oven and allow the bars to cool in the pan for 5–10 minutes.

Lift the bars out using the parchment paper and let them cool for another 15–20 minutes.

Cut into 9 square bars and serve.