Add garlic paste, then sugar, and cook for another minute.
Remove from heat and stir in flour to form a light roux.
Return to heat, add white wine, stock, and thyme; bring to a boil.
Simmer gently for about 25 minutes.
For the croutons, brush baguette slices with olive oil, garlic, and top with cheese. Bake until golden.
Ladle soup into oven-proof bowls, top with the cheesy toast, and bake for 5 minutes. Serve hot.