Preheat the oven to 425 degrees (400 if you are using the convection setting). Line a rimmed baking sheet with parchment paper.
In a medium bowl, toss potatoes with olive oil and sea salt, then spread out on baking sheet. Bake for 25 -30 minutes, until lightly browned and softened.
While potatoes are baking, make aioli. First chop garlic finely in a food processor using blade attachment. Then add remaining ingredients, adding basil last. Adjust salt and lemon juice to taste, and maybe add a few drops of olive oil to thin to desired consistency. Store in a tupperware for up to three days, but it'll be gone before then!
Take another baking sheet and align it with the sheet with your potatoes, and press down evenly. This does the job of smashing all of the potatoes at the same time, and feels so satisfying! You can go back through and individually smash some more tatties if they’re not flattened enough, but this is a good first pass.
Pop them back in the oven for 3-5 minutes to get them nice and crispy.
Top liberally with dollops of garlic basil aioli and enjoy!