Pour oil into a Dutch oven set over medium heat. Add bacon and cook until crisp. Using a slotted spoon drain bacon onto paper towels and set aside.

Add the sausage to the bacon grease and cook, breaking up into bite sized pieces with a wooden spoon, until browned.

Transfer sausage to a bowl using a slotted spoon.

Remove all but 3 tablespoons drippings to dutch oven and place back over medium heat. Add onion, celery and carrot. Sauté vegetables for about 3 to 4 minutes. Season with salt and pepper.

Add potatoes, garlic, ¼ teaspoon crushed red pepper flakes and thyme. Sauté until the garlic is fragrant, about 1 minute.

Sprinkle flour over the vegetables and cook, stirring constantly, until the flour is evenly distributed and begins to brown on the bottom of the pot, 3 to 4 minutes.

Stir stock into pot, scraping up any browned bits on the bottom. Season with salt and pepper.

Bring the soup to a boil over medium-high heat, then reduce the heat to medium-low and simmer, stirring occasionally until the potatoes are just tender, about 15 minutes.

Stir milk, kale and sausage to the pot until evenly distributed. Cook gently, stirring occasionally, until the kale is softened and the soup is heated through about 5 minutes. Season with salt and pepper as needed and stir.

Serve immediately in bowls garnished with shaved parmesan, crumbled bacon and crushed red pepper flakes.