Heat the olive oil in a large pot or Dutch oven over medium-high heat until shimmering. Add the crumbled chicken sausage and cook, breaking it into small pieces, for 6 to 8 minutes until browned and cooked all the way through. Transfer to a bowl, cover to keep warm, and leave the browned bits in the pot.

Reduce the heat to medium. Add the butter and let it melt. Add the diced onion, red pepper, and carrots and cook for 2 to 3 minutes, stirring, until they start to soften.

Sprinkle in the flour and add the crushed garlic. Cook for 1 minute, stirring constantly, until the flour disappears into the vegetables and smells fragrant. Don't let the garlic brown.

Keep the heat at medium and pour in the white wine, scraping up the browned bits from the bottom of the pot. Let it bubble for about 30 seconds.

Add the chicken broth, milk, bouillon, Italian seasoning, salt, red pepper flakes, and the Parmigiano Reggiano rind if using. Raise the heat to medium-high, bring to a gentle boil, and cook for 3 minutes, stirring occasionally, until the broth looks slightly thickened and creamy.

Return the sausage to the pot.

Add the pearl couscous and stir. Keep the soup at a gentle boil and cook for 5 minutes, stirring occasionally, until the pearls are plump and tender.

Reduce the heat to medium-low. Stir in the baby kale or spinach and simmer for 2 minutes, until wilted. Remove the rind if you used one. Taste and adjust the salt. Remove the parm rind.

Ladle into bowls. Top with freshly grated Parmigiano Reggiano, fresh basil, and a pinch of red pepper flakes.