I recommend letting the dough rest in the fridge for 24 hours or overnight for better flavour. But if you plan on baking them right away, go ahead and preheat your oven to 165°C/330°F and line a baking sheet with a silicone mat or parchment paper.
Lightly toast the almond powder in the oven or in a pan on the stovetop until golden and place in a medium sized bowl. It burns easily on the stovetop so keep an eye on it. In the meantime, in a small bowl, whisk together the flour, baking soda, baking powder and salt.
Chop up the bar of chocolate into small pieces if that’s what you’re using.
To the almond powder, add the oil, sugars, cornstarch, milk and vanilla and whisk all together until smooth.
Add the flour mixture and chocolate to the wet ingredients and mix until an even cookie dough forms.
I like slightly bigger cookies so I weigh them at about 60g, but if you like them smaller you can weigh them at around 40g (if you want to weigh them at all that is). Place them on the lined baking sheet with enough room in between for spreading.
Sprinkle with the coarse salt, bake for about 12-15 minutes and leave them to cool on the baking sheet until they’ve set enough to move them to a wire rack.
Pan-banging: Every minute of two during the bake time tap the pan on its rack in the oven a few times to promote spreading and rippling. You can also take the pan out to do this. You may need to add a few minutes to the bake time.You can also do it just once midway through baking and once when you take them out at the end if you don’t want your cookies so thin.