To prepare the croutons, preheat the oven 325° degrees F.
Whisk the butter, rosemary, garlic, and nutritional yeast in a large bowl until well combined - it will look kind of like a paste. Once combined, add the bread cubes into the bowl and toss until they're fully coated, 1 to 2 minutes.
Place the croutons on a rimmed baking sheet lined with parchment paper and bake on the middle rack of the preheated for 12-15 minutes, flipping halfway through. Reduce the oven temperature to 275° degrees F., and continue to bake for an additional 10-15 minutes, until golden brown and crispy.
Meanwhile, get started on the soup. Melt the butter in a medium stock pot over medium-low heat. Once the butter is melted, add the flour, and stir until thoroughly combined. continue to cook, stirring often, until the roux turns a light golden color, 3 to 5 minutes.
Add the leeks, carrot, celery and garlic and sauté, stirring often, until the onions become slightly translucent, 4 to 5 minutes. Slowly pour in the ale and simmer another 5 minutes. Add the pumpkin puree, broth and soy milk and season with the salt, pepper, nutmeg, and cayenne (if using). Increase the heat to medium, and simmer uncovered, stirring often, until the soup thickens, about 10 minutes.
Add the cheese and stir until it's melted through.
Serve with with a handful of rosemary croutons and fresh minced parsley. ENJOY!