Heat a large soup pot over medium-high heat, then add the bacon lardons. Cook, stirring occasionally, until the bacon is crispy. Use a slotted spoon to transfer to a paper towel-lined bowl.
To the same pot, add 2 Tbsp butter and chopped onion. Cook, stirring occasionally, until softened. Add chopped garlic, then cook.
Stir in flour, then whisk until the flour has been fully absorbed into the fat. Continue whisking, then pour in chicken broth. Bring the mixture to a boil.
To the pot, add corn kernels, cubed potatoes, fresh thyme, and a bay leaf. Season with Kosher salt, black pepper, and cayenne. Once simmering, cover the pot and cook. For a stronger corn flavor, add some of the corn cobs directly to the soup pot.
Remove the thyme, bay leaf, and corn cobs, then carefully transfer half of the soup to a blender and process until very smooth. Return the puréed soup to the pot. Alternatively, you can use an immersion blender to blend about half of the soup.
Add heavy cream and most of the crispy bacon to the pan, then stir well. Taste and adjust seasoning as needed. Serve corn chowder immediately with additional crispy bacon, thinly sliced chives, a pinch of flaky sea salt, and some freshly ground black pepper on top.