Turn up the heat to medium-high, bring it to a boil, then reduce to medium-low and simmer for 5-10 minutes until it slightly thickens.
Heat butter in a medium-sized stockpot over medium heat until it melts evenly.
Sauté minced onion and garlic until they turn soft, which should take about 5 minutes.
Allow it to cool slightly, then gradually stir in heavy cream and shredded cheese until fully melted.
Add chili powder, paprika, cumin, crushed tomatoes, and 3 ½ cups of chicken broth.
Combine cornstarch with the remaining ½ cup of chicken broth in a small bowl and then add it to the pot.
Return the pot to heat, mix in, and let it simmer for a0 minutes.
Serve the soup in bowls and garnish.