1. reheat oven to 400°F (200°C).
2. Toss broccoli florets with 1 tbsp oil, salt, and pepper. Spread on a baking sheet and roast for 20-30 minutes until golden brown.
3. In a large saucepan, heat 1 tbsp oil over medium heat. Add onion and sauté until tender (5-7 minutes).
4. Add garlic and thyme; sauté for 1 minute until fragrant.
5. Pour in the broth and roasted broccoli. Bring to a boil, then reduce heat and simmer, covered, for 20 minutes.
6. Use an immersion blender to puree the soup to your desired consistency.
7. Stir in cheddar cheese, allowing it to melt without boiling.
8. Mix in milk and mustard (if using), season with salt and pepper, and remove from heat.
9. Serve warm, garnished with extra cheese or croutons if desired.

Slow Cooker Method:

• Follow Step 1. Optionally complete Steps 2-3.
• Place all ingredients (except milk and cheese) in a slow cooker.
• Cook on low for 6-10 hours or high for 2-4 hours.
• Stir in milk and cheese before pureeing the soup.