In a large saucepan or pot, heat the olive oil over medium heat. Add the leeks and garlic and 1 teaspoon of kosher salt, cooking and stirring until soft (no need to brown!)
2 tablespoons olive oil, 2 leeks (white and light green parts!), 2 garlic cloves, kosher salt
Add the cauliflower, potato, thyme and broth. Bring to a boil, then reduce the heat to a simmer and cook until the cauliflower and potato is falling apart.
1 head cauliflower, 2 large potatoes, 2 teaspoon dried thyme, 4 cups vegetable broth
Remove from the heat and blend either in a blender or with a hand held immersion blender.
Return to the pot and add the cheese. Stir until the cheese has melted. Season with salt and pepper. You can add a dollop of sour cream, croutons and chopped chives or thyme.
1 cup sharp cheddar cheese
Notes
Cheese: I used a sharp cheddar cheese but feel free to use a milder cheddar if you prefer.
Seasonings: adjust the herbs and spices according to what you like! Storage: Store the cooled soup in an airtight container for up to 5 days. Reheat in the microwave or in a saucepan on the stove until warm.