Buttery orange chocolate crumble bars with a rich chocolate filling and soft, melt-in-your-mouth texture. Easy to make and perfect warm with coffee or vanilla ice cream.
Preheat the oven to 180°C (350°F). Line an 8-inch (20 cm) square pan with parchment paper.
Add the flour, powdered sugar, almond flour, cornstarch, and salt to a food processor. Pulse briefly to combine.
Add the vanilla extract and cold butter. Pulse until the mixture looks sandy.
Add 1 tablespoon cold milk (or water) and pulse just until the dough forms larger crumbs that hold when pressed. Do not overmix. (If needed, add up to 1 more tablespoon, but stop as soon as crumbs form.)
Press two-thirds of the crumble mixture firmly into the prepared pan. Bake for 10–15 minutes, until lightly golden.
Remove from the oven and immediately spread the Nutella evenly over the warm base.
Add the orange zest to the remaining crumble mixture and gently mix it in with your fingers.
Sprinkle the orange crumble evenly over the chocolate layer.
Bake again for 17–20 minutes, until golden.
Let cool before slicing. Serve as is, dusted with powdered sugar, or slightly warm.